Shielded vs unshielded cable, how to choose the answer here!

Shielded cable vs unshielded cable

Shielded cable? Or unshielded cable—— This is a problem. The choice of shielded or unshielded cables mainly depends on the specific application requirements. Today, Xiaobian sorted out the factors that should be considered when using shielded cables on AAC Cable treasure.
01
PART
Shielded cable
Shielded cable is a transmission line that uses metal mesh braid to wrap the signal line. The braid is generally red copper or tinned copper; Shielded cables are mainly used to prevent interference signals from entering the inner conductor and are suitable for transformers and similar equipment.
The shielded cable complies with the national standard: gb12972.6-91. The long-term allowable working temperature of the conductor is 90 ℃. It is suitable for the connecting wires of control and monitoring circuits and protection lines with rated voltage of 450 / 750V and below. It is mainly used in places where electromagnetic wave interference is prevented and shielding is required.
In order to minimize the impact of electromagnetic and radio frequency interference, each component in the shielding system must be seamless and correctly installed and maintained. In addition, shielded cables and systems also need good grounding. Incorrect grounding can cause radiation and interference problems in the system.

Single layer shielding

double-layer screen
Shielded stray wire
Single layer shielding
double-layer screen
Shielded cable assembly
02
PART
Unshielded cable
When wiring near EMI / RFI interference sources is not involved, unshielded ACSR Cables shall be selected in most cases. Unshielded cable has the advantages of light weight, high flexibility, wide use, reliability and low price. It is widely used in IT applications and office networks.

Unshielded dispersion
picture
Unshielded cable assembly
However, it should be noted that when enterprise networks or SMB networks want to achieve high data rates such as 10Gbps or 40Gbps on copper wires, the use of shielded cables can significantly reduce or even eliminate external crosstalk (AXT) harmful to network performance. This problem is mainly aimed at high-speed networks using category 6 cables, and does not involve low-speed 10 / 100 / 1000 networks using category 5 and category 6 cables.
It can be seen that the type of cable selected depends on the physical location of the network and the technology adopted (such as 10Base-T). The best practice is to thoroughly evaluate the installation location and network technical requirements, and then select the appropriate cable according to the specific specification requirements.

What are the effects of temperature on cable selection?

Whether our colleagues in electrical design or factory electrical maintenance can not open the topic of cable selection, we often see that the AAC Cable selection size of the same equipment under the same power will be different in the work, some may be less than one or two levels, and some friends may be confused by which right? Why do you choose different? Today we will learn how to choose the cable and how to consider it from? What is the effect of temperature on the selection of cables?


1、 Cable selection
(1) Select cable according to temperature rise
We all know that when the conductor passes through the load current, the temperature of the conductor will rise, the conductor has insulation layer, and the conductor temperature shall not exceed the maximum temperature allowed for a long time by the conductor insulation, and the conductor will be damaged after exceeding.
(2) According to mechanical strength
When laying, the conductor has a minimum section allowed according to the laying mode and the distance between the support point and the distance.
(3) Select according to economic conditions
That is, choose the most economical way.
(4) Select by line voltage drop
We all know that when the current passes through the conductor, the voltage drop will be generated in the line due to the existence of line impedance. If the voltage drop is too large, the voltage at the end of the line, that is, the load end is too low, which will cause the equipment to fail to work or affect the equipment life. Therefore, it is required that the voltage drop cannot be too large, so the cable section should be selected reasonably.

(5) Cable selection shall meet the requirements of load protection
When the circuit is in fault, the protective device should act according to the specified time, whether it can operate reliably or not has a great relationship with the cable section. Therefore, we should consider the requirements of reliable action when choosing the ACSR Cable.
(6) Select cable according to the requirements of thermal stability
In case of failure of cable or electrical equipment, the cable shall meet the requirements of thermal stability, and the size of cable section shall be considered in order to meet this requirement. The maximum cross section is the final result by combining the above conditions.

What are the maintenance items of bridge cable and special cable bridge?

Project Name: design and processing of high voltage ACSR Cable bridge
Innovative ideas: there are three 10kv High-voltage incoming lines for 112201 fully mechanized coal mining face, which are laid from 11 panel substation to equipment train of working face. The high-voltage cable enters the rubber conveying chute section and is suspended along the coal wall side. From the coal wall side to the cable storage vehicle, it needs to cross the belt.

Therefore, the design and processing of the bridge will cross the high-voltage cable belt into the cable storage vehicle.

Design principle: I-steel is used to process the bridge, the lower part is fixed with the equipment train pole, the high voltage cable is laid from the I-steel groove, and the protective skin is padded at the lower part of the cable.
Expected effect: after the processing, installation and use of the cable bridge, the three high-voltage cables inside the belt are smoothly led across the belt to the high-voltage cable car, and the cable bridge is integrated with the equipment train, each time the equipment is pulled and moved, there is no need to re hang the high-voltage cable, saving working hours.
(1) Check whether the cables on both sides of the bridge are under large tension.

(2) check whether there are cracks, oil leakage and corrosion on the cables on both sides of the bridge.
(3) whether the AAAC Cable, protective tube and groove are damaged by collision or external force.
(4) paint bracket and exposed protective pipe and groove.
(5) check the cable armour cover.

Learn cable knowledge, start here

1、 Basic introduction of wire and cable
Wire and cable: usually twisted by several wires or groups of wires [at least two in each group], similar to rope. Each group of wires is insulated from each other and twisted around the center of a wire. The whole wire is covered with a highly insulating covering layer. It is mainly used for transmission, distribution of electric energy or transmission of electric signals.
Wires and ACSR Cables are mainly composed of the following four parts
1. Conductive core: made of high conductivity material (copper or aluminum). According to the requirements of laying and using conditions for cable flexibility, each wire core may be made of a single wire or multiple wires.
2. Insulating layer: the insulating material used for cables shall have high insulation resistance. The common insulation materials used in cables are oil impregnated paper, PVC, PE, XLPE, rubber, etc.


3. Sealed sheath: protect insulated wire core from mechanical, moisture, moisture, chemicals, light and other damage. For the insulation susceptible to moisture, lead or aluminum extrusion sealing sheath is generally used.
4. Protective coating: used to protect the sealing sheath from mechanical damage. Generally, galvanized steel strip, steel wire or copper strip, copper wire, etc. are used as armor to wrap around the sheath (called armored cable), and the armor layer plays the role of electric field shielding and preventing external electromagnetic interference at the same time. In order to avoid the corrosion of steel strip and steel wire by the surrounding medium, they are usually coated with asphalt or wrapped with impregnated jute layer or extruded with polyethylene or PVC sleeve.
2、 Wire and cable specifications
Wire and cable specification is the meaning of the expression of the number of cores and section size of wire and cable. The complete naming of wires and AAC Cables is usually more complex, so people sometimes use a simple name (usually the name of a category) combined with model specifications to replace the complete name. For example, “low voltage cable” represents all plastic insulated power cables of 0.6/1kv class. It can be said that as long as the standard models and specifications of wires and cables are written, specific products can be identified.
3、 Wire and cable application classification
(1) Classified by insulating materials, such as oil impregnated paper insulated cable, PVC cable, XLPE cable, etc.
(2) According to the use classification, it is divided into power cable, communication cable and control cable. They are used in power system, information transmission system, mechanical equipment and instrument system.
1. Power system
The wire and cable products used in power system mainly include overhead bare wire, bus bar (bus bar), power cable (plastic cable, oil paper power cable (basically replaced by plastic power cable), rubber sheathed cable, overhead insulated cable), branch cable (replacing part of bus bar), electromagnetic wire and electric equipment wire and cable for power equipment.


2. Information transmission system
The wires and cables used in information transmission system mainly include local telephone cable, television cable, electronic cable, radio frequency cable, optical fiber cable, data cable, electromagnetic wire, power communication or other composite cables.
3. Mechanical equipment and instrument system
Except for overhead bare wires, almost all other products have applications, but mainly power cables, electromagnetic wires, data cables, instrument cables, etc.
(3) According to product classification, it can be divided into five categories
1. Bare wire and bare conductor products
The main features of this kind of products are: pure conductor metal, no insulation and sheath layer, such as ACSR, Cu al bus bar, electric locomotive line, etc; The processing technology is mainly pressure processing, such as melting, calendering, drawing, stranding / tight stranding, etc; Products are mainly used in suburbs, rural areas, user main line, switch cabinet, etc.
2. Power cable
The main features of this kind of products are: extruding (winding) the insulating layer outside the conductor, such as overhead insulated cable, or twisting several cores (corresponding to the phase line, zero line and ground wire of power system), such as overhead insulated cable with more than two cores, or adding sheath layer, such as plastic / rubber sheathed wire and cable. The main process technologies include drawing, stranding, insulation extrusion (wrapping), cabling, armor, sheath extrusion, etc. different process combinations of various products have certain differences.
The products are mainly used in the transmission of strong electric energy in power generation, distribution, transmission, transformation and power supply lines, with large current (tens to thousands of a) and high voltage (220 V to 500 kV and above).
3. Wires and cables for electrical equipment
The main features of these products are: a wide range of varieties and specifications, a wide range of applications, the use of voltage in 1kV and below more, in the face of special occasions continue to derive new products, such as fire-resistant cable, flame retardant cable, low smoke halogen-free / low smoke halogen-free cable, termite proof, mouse proof cable, oil / cold / temperature / wear-resistant cable, medical / agricultural / mining cable, thin-walled wire, etc.
4. Communication cable and optical fiber
From simple telephone and telegraph cables in the past to thousands of pairs of telephone cables, coaxial cables, optical cables, data cables, and even combined communication cables. This kind of product structure size is usually small and uniform, high manufacturing accuracy requirements.
5. Electromagnetic wire (winding wire)
It is mainly used for various motors, instruments, etc.
4、 What’s the difference between wire and cable?
In fact, there is no strict boundary between “wire” and “cable”. Generally, the products with few cores, small diameter and simple structure are called wires, the ones without insulation are called bare wires, and the others are called cables; The conductor with larger cross-sectional area (more than 6 square mm) is called large wire, the smaller one (less than or equal to 6 square mm) is called small wire, and the insulated wire is also called cloth wire. But with the expansion of the scope of use, many varieties of “cable in the cable”, “cable in the cable”. So there is no need to make a strict distinction. In daily habits, people call household cloth wires wires and power cables for short.
The wire is composed of one or several soft wires with light and soft protective layer; The cable is composed of one or several insulated wires, which are wrapped with a tough outer layer made of metal or rubber. Cables and wires are generally composed of core wire, insulation sheath and protective sheath.

What is the valve performance of the sheath protector?

In order to ensure that the sheath insulation will not be damaged under the action of lightning overvoltage and switching overvoltage, the sheath protector should be used. The ball gap protector was used in the early stage, but its disadvantage was that its surface was burnt by power frequency afterflow after each action. This type is not only heavy maintenance, but also unreliable. At present, zinc oxide, a non-linear resistor, is widely used in sheath protectors.
under normal operation, the current flowing through the sheath protector is microampere, so as to ensure the reliable operation of the AAC Cable.


Function of cable sheath Protector:
1. Limit the power frequency induced voltage in the metal sheath of ACSR Cable line.
In the normal working state of the cable line, the high-voltage cable sheath protector presents a high resistance state, which cuts off the power frequency induced current circuit in the cable metal sheath.
2. The power frequency and impulse overvoltage in the metal sheath of cable line can be reduced rapidly.
When grounding fault, lightning over-voltage or internal over-voltage occurs in the cable line, which leads to high over-voltage in the metal sheath, the sheath protector presents a low resistance conduction state, which makes the fault current quickly pour into the earth through the protector.


Selection of cable sheath Protector:
1. The residual voltage under the action of the possible maximum impulse current shall not be greater than the value of [impulse withstand voltage of cable sheath] – (37.5kv for 110kV cable) divided by 1.4 (included in the insulation coordination coefficient).
2. The possible maximum power frequency overvoltage shall be able to withstand without breakdown or damage under the action of 5S.
3. The protector shall not be damaged after 20 times cumulative action of the maximum possible impulse current.
Regular inspection and maintenance of cable sheath Protector:
Regularly measure the DC reference voltage of cable sheath protector at 1mA and the leakage current at 0.75 times of the reference voltage, especially after the system failure.

How to prevent cable corona discharge?

Corona discharge occurs in the air gap of indoor heat shrinkable, cold shrinkable or nylon AAC Cable terminal due to the action of electric field at the junction of semiconductor shielding layer and insulation layer of three core or single core cable.
When the terminal position of the cable installed in the indoor switch cabinet or metering cabinet of the distribution station is low, the ponding in the cable trench or the poor ventilation of the distribution station, and the indoor air humidity is high, the corona discharge phenomenon will also occur.
In order to prevent the corona discharge of indoor terminal, the filling material of trident of three core cable terminal must be filled. In addition to the filling material, the heat shrinkable or cold shrinkable terminal should also pay attention to the elimination of gas in the pipe during the heat shrinkable or cold shrinkable process without leaving air gap. Special attention should be paid at the junction of the two media.
The experimental results show that after the heat shrinkable terminal is moved, the discharge amount of partial discharge test will increase, and the re heating shrinkage partial discharge will decrease. Therefore, if corona discharge occurs at the heat shrinkable terminal, it will disappear after reheating and shrinking to eliminate the air gap.

If the cable trench in the station is flooded and the ventilation is poor, measures such as drainage, improving ventilation and keeping the station environment clean shall be taken( The above text is excerpted from “technical questions and answers for power cable installation and operation”)
reference:
[1] Shi Chuanqing, chief editor. Question and answer of power ABC Cable installation and operation technology. Beijing: China Electric Power Press, 2007
Extended reading:
Corona discharge, the most common form of gas discharge, refers to the partial self-sustaining discharge of gas medium in non-uniform electric field. In the vicinity of the tip electrode with a small radius of curvature, the local electric field intensity exceeds the ionization field intensity of the gas, which makes the gas ionize and excite, resulting in corona discharge. When corona occurs, light can be seen around the electrode, accompanied by a hissing sound. Corona discharge can be a relatively stable discharge form, or it can be an early development stage in the process of gap breakdown in uneven electric field.

When multiple cables run in parallel, the load distribution will be uneven?

When multiple cables are running in parallel, load measurement shall be conducted regularly to understand the load distribution and correctly grasp the operation status of ACSR Cables.


The load distribution of multiple cables is uneven when running in parallel, and even one phase load of one cable will be close to zero. The main reason for the serious uneven load distribution is the large difference of contact resistance of terminal connection (especially outdoor copper aluminum transition contact).
Because, the corrosion battery with two different metal contacts will cause poor contact; Due to the change of load current, temperature and natural environment, contact resistance of contact will increase to different extent. In this way, the current distribution is not uniform. For example, three cables a, B and C are running in parallel. If the contact resistance of cable a contact is large, the current is small and the normal load is mostly transferred to ABC Cables B and C. This may cause overload of cable B and C. if the contact of cable B terminal is heated due to the increase of load, the contact will be burnt and the load will be transferred to cable C, resulting in overload, thus forming a vicious cycle, and even heating will be caused by serious uneven distribution of three-phase current on the cable armour. This phenomenon will certainly endanger the safe operation of cable lines, and should be paid full attention.


Note: in design, the cable model and path length used in parallel are the same in general. Even if the models are different, the current distribution problem will be considered to meet the actual operation requirements. The provisions of this article are designed to consider that different types of cables are used for laying parallel cables due to tight construction period and incomplete cable goods, which may cause overload of one cable and insufficient load of another cable to affect operation safety. Because of the different insulation types of cables, the maximum allowable operating temperature of the core is different, and the allowable carrying capacity of the cables with the same material and specification and different insulation types is also different. Therefore, if different types of cables are used in construction, the length of cables shall be the same as possible during laying, so as to avoid the impact of operation safety due to the disproportionate distribution of load.

For more information on cables, click Joy ’cable Blog

Instruments and accessories for cable path detection


Figure 6 t5000-3 transmitter and receiver
Instrument: t5000-3 color screen intelligent pipeline instrument
Signal output part: transmitter, direct connection, coupling clamp, LCC module
Direct connection: direct connection signal output line, used when finding the route of power cut cable
Coupling clamp: clamp method signal output line, used when finding live cable path
LCC module: it can isolate the AC voltage of 480v and below, and cooperate with transmitter to connect the AAC Cable with direct connection method, and find the live low voltage cable path and transmission cable path.
picture
Figure 7 transmitter accessories
Receiving signal part: receiver, stethoscope, A-frame

Figure 8 receiver accessories
Stethoscope: it can be used in cooperation with receiver to identify the ABC Cable live and find the target cable from multiple cables;
A-Frame: it can be used in combination with receiver to accurately locate the fault point of buried cable, and the use method is step voltage method.

3、 Transmitter wiring method
1. direct connection method
It is suitable for finding the route of power cut cable, with high current and strong signal. The transmitting signal is injected into the primary core through the direct connection, and the test phase core at the end of the cable is grounded manually. The primary core and the earth constitute the test circuit, as shown in Figure 9 below.

Figure 9 schematic diagram of direct connection
Tips:
1. the signal can not be transmitted between phases (short circuit at the end) and the test circuit can not be formed by phase. Because the current signal is in the opposite direction, the magnetic field signal is offset. The receiver is essentially the received loop magnetic field signal, and the signal will not be received;
2. the armored ground on both sides of the cable shall be removed, otherwise the current signal transmitted will be transmitted back from the armor, which will also offset the magnetic field signal;
3. in a word, the test circuit shall be one-way and only circuit.
If the cable circuit is connected incorrectly, such as poor grounding, phase sequence error, etc., the transmitter has no output current or low output current, and the “indicating square” is blank, as shown in Figure 10 below. If the circuit is connected correctly, the output current of transmitter can reach 25mA, and the “indicating square” turns black, as shown in Figure 11 below.

Figure 10 display of transmitter with wrong circuit connection
2. clamp method
It is suitable for finding the route of stop and live cable, with small current and weak signal. The transmission voltage signal is induced to the high voltage cable armour or low voltage cable zero line through coupling clamp. As shown in Figure 12, since both ends of the cable are armored or zero wire are grounded, there will be stable current signal naturally.
Tips:
1. the same point between direct connection method and clamp method is that the magnetic field signal is generated by unidirectional stable current circuit. The difference is that direct connection method transmits signal in cable core through direct connection, and clamp method is used to couple transmission signal in cable armour or zero line through clamp coupling;
2. clamp method is relatively weak in signal application, and direct connection method is preferred for power cut cable;
3. for high voltage single core live cable, direct connection method can be used to find the path in aluminum sheath. The use of clamp method and direct connection method should be reasonably selected in combination with the grounding mode of aluminum sheath.
3.1 380V cable test method
380V power off cable:
① The direct connection method of conductor is shown in Figure 9, and the one-phase core is selected as the test phase, and the end of the line core is grounded with corresponding phase core, and the zero line grounding at both ends is removed. The fire line and terrain are single-phase and unique circuit;
② Zero line direct connection method: remove zero line grounding at one end of cable, and keep zero line grounding at the other end. The direct output line is connected to the suspended zero line, and the zero line and terrain are single-phase and unique circuit, as shown in Figure 13 below;

Figure 13 zero wire direct connection
③ Clamp method, as shown in Figure 12, the output clamp is directly stuck in the cable body or cable zero line, and the signal circuit is formed between the zero line and the ground. Note: at this time, the zero line at both ends of the cable should be grounded.
380V live cable:
① Clamp method, the wiring is the same as above;
② LCC, live direct connection, transmitter on the user side directly outputs the signal on the live fire line through LCC module. For 380 power supply low voltage power supply system, neutral point of transformer in the station area is directly grounded. At this time, the live fire line and the ground form a loop. Note: this method can only be used in the user side wiring, and find the cable path from the power side, The site case is referred to the above official account.
3.2 10kV cable test method
10kV power off cable:
① The direct connection method of conductor is shown in Figure 9, and the one-phase core is selected as the test phase, and the end of the corresponding phase wire core is grounded, and the armored grounding at both ends is removed. The conductor and terrain are single-phase and unique circuit;
② Armor direct connection method: remove the armored grounding at one end of the cable, and keep the armored grounding at the other end. The direct output line is connected to the suspended armored lead wire, and the armor and terrain are single-phase and unique circuit, as shown in Figure 14 below;
③ Clamp method, as shown in Figure 12, shows that the output clamp is directly stuck on the cable body or cable armored ground wire, and the signal circuit is formed between the armor and the ground. The clamp connection demonstration is shown in Figure 15 below.
10kV live cable:
Clamp method, same as above.
3.3 test method of 110kV cable
110kV power off cable:
① Direct connection of conductors, as above;
② For the direct connection method of aluminum sheath, the grounding mode of aluminum sheath shall be referred to. For the single end grounded cable section of aluminum sheath, the direct connection signal of aluminum sheath coaxial cable conductor shall be directly connected at the protective grounding box; For the cross connected cable section with aluminum sheath, the conductor or shielding direct connection signal of aluminum sheath coaxial cable shall be conducted at any cross interconnection box.
110kV live cable:
① For the cable section with single end grounding of aluminum sheath, open the protective grounding box or cross connected box with no grounding end. First, use multimeter to measure the induced voltage of the aluminum sheath. If the induction voltage is less than 25V (t5000-3 fuse fuse fuse fuse fuse fuse voltage), direct connection method can be directly used for aluminum sheath, as shown in Figure 16 below;
② If the induction voltage of aluminum sheath without grounding terminal exceeds 25V, LCC module incoming voltage shield shall be used and the live direct connection method shall be used for test;
③ Clamp method: because the aluminum sheath of cross connected large section is directly grounded at both ends, although the cable is transposed, the overall aluminum sheath still forms a circuit with the ground. Therefore, clamp method is only applicable to the path finding of 110kV cable section cross connected by aluminum sheath, and clamp the clamp directly on the coaxial cable at the cable body or any grounding box, as shown in Figure 18 below.
Tips:
1. when finding the path of 110kV cable live, it is better to search by sections according to aluminum sheath, and apply signal from the ground end to find the cable path to the grounding end;
2. for the cable section with no grounding at the direct grounding end of one end of aluminum sheath, the clamp method signal is weak. At this time, the output power of transmitter shall be increased and the output frequency shall be adjusted to test. It is recommended to use direct connection method or live direct connection method for finding out the ungrounded end;
3. because 110kV single core cable will generate induction voltage on aluminum sheath, if clamp is directly stuck on cable body, inductive voltage will also be generated in clamp. At this time, if clamp jaws are completely closed, circulation will be formed on clamp coil, and clamp will be burned by heating, that is, paper sheet shall be pad for closing jaw, as shown in Figure 19 below.

Figure 19 jaw treatment of clamp method when using the body

How to solve these problems in PVC

1、 Troubleshooting of common faults in injection molding of ACSR Cables
Under note
Fault analysis and Troubleshooting:
(1) The temperature of the melt is too low. The forming temperature should be increased properly.
(2) Forming cycle is too short. It should be extended appropriately.
(3) Insufficient injection pressure. It should be improved appropriately.
(4) The injection rate is too slow. It should be accelerated appropriately.
(5) Insufficient supply. The supply shall be increased.
(6) The temperature of the die is too low, so it should be properly raised. In particular, the cooling circuit of the mold should be set reasonably to keep the temperature of the mold uniform.


(7) The shape and structure of plastic parts are not designed reasonably or the wall is too thin. Adjustments should be made in the event of possible changes.
(8) The structure size of the pouring system is small. Gate and runner sections shall be enlarged appropriately.
(9) The exhaust of the mold is poor. The exhaust hole should be added to improve the exhaust performance of the AAAC Cables.
(10) The strength of the die is not enough. The rigidity should be improved as much as possible.
· shrinkage marks
Fault analysis and Troubleshooting:
(1) The barrel temperature is too high. The barrel temperature shall be properly reduced.
(2) Insufficient injection pressure. It should be improved appropriately.
(3) The holding time is too short. It should be extended appropriately.
(4) The cooling time is too short. The cooling efficiency shall be improved or the cooling time shall be prolonged.
(5) Insufficient supply. The supply shall be increased.
(6) The temperature of the die is not uniform. The cooling system of the mould should be adjusted and the cooling circuit should be set reasonably.
(7) The shape structure design of plastic parts is unreasonable or the wall of plastic parts is too thick. Adjustments should be made where possible.
(8) Gate cross section is too small. It should be increased appropriately.
· weld marks
Fault analysis and Troubleshooting:
(1) The temperature of the melt is too low. The forming temperature should be increased properly.
(2) Insufficient injection pressure. It should be improved appropriately.
(3) The injection rate is too slow. It should be accelerated appropriately.
(4) The temperature of the die is too low, so it should be properly raised.
(5) The gate section is too small. It should be increased appropriately.
(6) Poor exhaust of mould. The exhaust hole should be added to improve the exhaust performance of the die.
(7) The structure size of cold material hole is too small or the position is not correct. It should be adjusted reasonably.
(8) Impurities are mixed in the raw materials. Foreign matters and impurities shall be removed thoroughly or new materials shall be used.
(9) The dosage of release agent is too much. The amount of the product should be minimized.
(10) The insert is not set up reasonably. It should be adjusted appropriately.
(11) The raw material is not uniformly colored. The colorant with good dispersibility and the mixing time should be prolonged to make the raw material coloring even.
Flow marks
Fault analysis and Troubleshooting:
(1) The temperature of the melt is too low. The forming temperature should be increased properly.
(2) Insufficient injection pressure. It should be improved appropriately.
(3) The holding time is too short. It should be extended appropriately.
(4) The temperature of the die is too low, so it should be properly raised.
(5) The temperature of the die is not uniform. The cooling system of the mould should be adjusted and the cooling circuit should be set reasonably.
(6) Gate cross section is too small. It should be increased appropriately.
(7) The structure size of cold material hole is too small or the position is not correct. It should be adjusted reasonably.
(8) The raw material is not uniformly colored. The color additive with good dispersibility should be selected, and the mixing time should be prolonged.


Poor gloss
Fault analysis and Troubleshooting:
(1) The temperature of the melt is too low. The forming temperature should be increased properly.
(2) The molding cycle is too long. It should be shortened appropriately.
(3) Screw back pressure is too low. It should be improved appropriately.
(4) The temperature of the die is too low, so it should be properly raised.
(5) The structure size of the pouring system is small. Gate and runner sections shall be enlarged appropriately.
(6) Poor exhaust of mould. The exhaust hole should be added to improve the exhaust performance of the die.
(7) Impurities are mixed in the raw materials. Foreign matters and impurities shall be removed thoroughly or new materials shall be used.
(8) The dosage of release agent is too much. The amount of the product should be minimized.
(9) Raw materials are not fully dried. The drying temperature and time should be increased appropriately.
· bubbles
Fault analysis and Troubleshooting:
(1) The barrel temperature is too high. The barrel temperature shall be properly reduced.
(2) The molding cycle is too long. It should be shortened appropriately.
(3) Insufficient injection pressure. It should be improved appropriately.
(4) The injection speed is too fast. It should be slowed down appropriately.
(5) The holding time is too short. It should be extended appropriately.
(6) The temperature of the die is not uniform. The cooling system of the mould should be adjusted and the cooling circuit should be set reasonably.
(7) The shape structure design of plastic parts is unreasonable or the wall of plastic parts is too thick. Adjustments should be made where possible.
(8) Gate cross section is too small. It should be increased appropriately.
(9) The exhaust of the mold is poor. The exhaust hole should be added to improve the exhaust performance of the die.
(10) Raw materials are not fully dried. The drying temperature and time should be increased appropriately.
? uneven color
Fault analysis and Troubleshooting:
(1) The barrel temperature is too high. The barrel temperature shall be properly reduced.
(2) The molding cycle is too long. It should be shortened appropriately.
(3) The raw material is not uniformly colored. The color additive with good dispersibility should be selected, and the mixing time should be prolonged.
Burnt and black
Fault analysis and Troubleshooting:
(1) The barrel temperature is too high. The barrel temperature shall be properly reduced.
(2) The molding cycle is too long. It should be shortened appropriately.
(3) The injection pressure is too high. It should be reduced appropriately.
(4) The injection rate is too fast. It should be slowed down appropriately.
(5) Screw back pressure is too high. It should be reduced appropriately.
(6) Gate cross section is too small. It should be increased appropriately.
(7) The exhaust of the mold is poor. The exhaust hole should be added to improve the exhaust performance of the die.
(8) The dosage of release agent is too much. The amount of the product should be minimized.
(9) Raw materials are not fully dried. The drying temperature and time should be increased appropriately.
· overfill edge


Fault analysis and Troubleshooting:
(1) The temperature of the melt is too high. The temperature of the barrel and the nozzle shall be properly reduced.
(2) The injection pressure is too high. It should be reduced appropriately.
(3) The injection rate is too fast. It should be slowed down appropriately.
(4) The holding time is too long. It should be shortened appropriately.
(5) There is too much supply. It should be reduced appropriately.
(6) The closing force is insufficient. It should be improved appropriately.
(7) The mold temperature is too high. It should be reduced appropriately.
(8) The shape structure design of plastic parts is unreasonable, and should be adjusted appropriately in case of possible changes.
(9) The strength of the die is not enough. We should try to increase its rigidity.
(10) The insert is not set up reasonably. According to the shape of plastic parts and the structure of the mold, proper adjustment shall be made.
Warping and deformation
Fault analysis and Troubleshooting:
(1) The barrel temperature is too low. It should be improved appropriately.
(2) Forming cycle is too short. It should be extended appropriately.
(3) The injection pressure is too high. It should be reduced appropriately.
(4) The injection speed is too fast. It should be slowed down appropriately.
(5) The holding time is too long. It should be shortened appropriately.
(6) The mold temperature is too high. It should be reduced appropriately.
(7) The cooling system of the mould is not reasonable, and the cooling circuit should be set reasonably according to the cooling requirements of the plastic structure.
(8) Gate cross section is too small. It should be increased appropriately.
(9) The setting of ejector is unreasonable. The area of jacking out and the point of jacking shall be increased as much as possible.
(10) The strength of the die is not enough. We should try to increase its rigidity.
· delamination
Fault analysis and Troubleshooting:
(1) If the melt temperature is too low, the temperature of the barrel and nozzle should be increased properly.
(2) The injection rate is too fast. It should be slowed down appropriately.
(3) The mold temperature is too low. It should be improved appropriately.
(4) Impurities are mixed in the raw materials. Foreign matters and impurities shall be removed thoroughly or new materials shall be used.
? discoloration of the surface
Fault analysis and Troubleshooting:
(1) The barrel temperature is too high. It should be reduced appropriately.
(2) The molding cycle is too long. It should be shortened appropriately.
(3) The injection rate is too fast. It should be slowed down appropriately.
(4) Screw back pressure is too high. It should be reduced appropriately.
(5) The gate section is too small. It should be increased appropriately.
(6) Poor exhaust of mould. The exhaust hole should be added to improve the exhaust performance of the die.
(7) Impurities are mixed in the raw materials. Foreign matters and impurities shall be removed thoroughly or new materials shall be used.
2、 Troubleshooting of common faults in injection molding of soft PVC
Poor gloss on the surface of the product
Fault analysis and Troubleshooting:
(1) The processing temperature is too low, and the material is not plasticized. The processing temperature should be improved properly to improve the plasticizing effect.
(2) The mold temperature is too low. The mold temperature should be increased appropriately.
(3) The material fluidity is too bad, the raw material should be replaced or the raw material formula should be adjusted.
(4) The surface finish of mold cavity is too poor. The surface finish of mold cavity should be improved properly.
(5) During the forming process, the auxiliary agent precipitates, and forms scaling on the surface of the mold. The mold surface scale should be removed in time. If it is serious, the formula should be adjusted.
(6) Too much recycled material. The amount of recycled material shall be reduced appropriately.
(7) The material temperature is too high, and the resin is decomposed. The injection temperature should be reduced and the thermal stability system should be improved.
? shrinkage deformation
Fault analysis and Troubleshooting:
(1) The holding time is too short. The time of pressure preservation should be prolonged, especially when shrinkage occurs near the gate, the method of prolonging the pressure holding time can be used to solve.
(2) The pressure holding pressure is too low. The pressure holding time should be improved properly.
(3) Injection pressure is too low. Injection time should be improved appropriately.
(4) The molding temperature is too high. The forming temperature shall be reduced appropriately.
(5) The amount of feed is insufficient. The amount of feed shall be increased appropriately.
(6) The mold temperature is too high or the heating is uneven. The cooling efficiency of the mould should be improved.
(7) The mold is opened too early and the product cooling is insufficient. The cooling time of the product in the mold shall be extended.
(8) The thickness difference of the products is too big, and the parts of the thickness of the products in process are prone to sag shrinkage due to the insufficient pressure. The design of the product shall be modified.
(9) Gate cross section is too small. It should be increased appropriately.
Under injection, lack of material
Fault analysis and Troubleshooting:
(1) Injection pressure or pressure retaining pressure is too low. Injection pressure or pressure retaining pressure should be increased appropriately.
(2) The holding time is too short. The holding time shall be extended appropriately.
(3) The processing temperature is too low. The processing temperature should be raised appropriately.
(4) The injection rate is too slow. The injection speed should be increased appropriately.
(5) The temperature of the mold or nozzle is too low. The temperature of the mold or nozzle shall be increased appropriately.
(6) Impurities or decomposition are blocked at the nozzle. The injection molding machine nozzles shall be cleaned.
(7) The gate section is too small. It should be increased appropriately.
(8) The exhaust hole of the mold is blocked. The plug in the die vent should be removed.
(9) Injection rate of injection molding machine is too small. The injection volume should be increased appropriately.
Coking decomposition
Fault analysis and Troubleshooting:
(1) The injection temperature is too high, the material is coking and decomposed, and the focus of the product is formed with the injection mold of the molten material. The injection temperature should be properly reduced to remove foreign matters from the dead angle of the barrel and the runner.
(2) Injection speed is too high. The injection rate should be reduced properly.
(3) Impurities or decomposition are blocked at the nozzle. The injection nozzle shall be cleaned.
(4) The thermal stability of raw materials is too poor. The material should be replaced or the formula adjusted to improve the thermal stability system.
(5) The lubricant is not used enough. The lubricant dosage should be increased appropriately.
(6) Poor exhaust of mould. The die exhaust system should be improved.
(7) The gate section of the mold is too small. The gate section of the mold shall be expanded appropriately.

Is the thicker the cable insulation, the better?

Many friends may think that the thicker the AAC Cable, the better the insulation performance, the more durable the cable, and the better the quality. In fact, this idea is taken for granted, and there are some misunderstandings.
This is because the insulation performance of cables depends on the technical indicators. The state has strict technical standards for cables. Compared with the cable thickness specified in the national standards, it is unnecessary to say that if the cable thickness is thinner, even if it is thicker, it is also unqualified as long as it exceeds the specified value.

When the thickness exceeds the standard, the performance of the cable will be affected, such as the service life will be greatly shortened. Because when the cable is laid and put into use, it will be in the state of continuous power supply, and the heat will be generated in the process of power supply. If the thickness exceeds the standard, although the insulation looks better, the result is that the heat is difficult to dissipate( Learn more cable technology, please click here, a large number of dry goods waiting for you) with the accumulation of time, more and more heat accumulation, of course, will affect the normal service life of the cable.


When the situation is serious, it will even lead to short circuit, power failure, causing greater damage.
The so-called “too much is not as good as it can be”. Those who meet the national standards are the best.

For more information on cables, click Joy ’cable Blog