1 The four-pole switch is used for the transfer switch between the normal power supply and the standby generator.
2 The dual power transfer switch with residual current action protection shall adopt a four-pole switch. In the same grounding system, the two power transfer switches with residual current action protect the power switch of the lower stage should adopt four poles.
3 A four-pole switch should be used for the power switch between two different grounding systems.
4 Four-pole switch is strictly forbidden in TN-C system.
5 Functional switching devices that ensure power conversion must act on all live conductors, and it must not be possible to connect these power supplies in parallel unless the unit is specifically designed for this situation. In the case of total equipotential bonding, TN-S, TN-CS systems generally do not require a four-pole switch.
The power inlet switch of the 6 TT system should adopt a four-stage switch.
7 Four-pole switches should be used when there is a neutral line in the IT system.
Four types of 4P breakers:
The overcurrent tripping component is not installed in the 1N pole, the N pole is always on, and the N pole is not combined with the other three poles;
The overcurrent tripping component is not installed in the 2N pole, and the N pole is combined with the other three poles;
The 3N pole is equipped with a tripping component, and the N pole is combined with the other three poles;
The 4N pole is equipped with a tripping component, and the N pole is always on. The system that does not share the TN-C with other three poles is not suitable for the leakage protection switch. The N and PE lines in the TN-C system are combined into the PEN line. When a leakage fault occurs in the PEN line of the device casing, the leakage protection switch cannot detect the leakage fault.
The 3-pole leakage switch is used in the case of three-phase four-wire system, and trips as long as there is an unbalanced load current flowing. In this case, a 4-pole leakage switch must be used.
TT- adopts 4P
TN- adopts 3P
IT- adopts 3P
Selection of four-pole circuit breaker
It is necessary to use a four-pole circuit breaker in the following cases:
1. A system with dual power switching requirements must use a four-pole circuit breaker to meet the isolation requirements for maintenance, testing, and overhaul of the entire system;
2. The single-phase main switch of each household should use a two-pole switch with N pole (a four-pole circuit breaker is available);
3. The residual current action protector (leakage switch) must ensure that all live conductors in the protected circuit are disconnected. Therefore, for circuits with residual current action protection requirements, N poles (such as four poles) should be used. Leakage circuit breakers.
At present, there are six types of four-pole plastic case circuit breakers supplied by the domestic market:
1. The N pole of the circuit breaker does not have an overcurrent release, and the N pole is combined with the other three phase lines to form a circuit;
2. The N pole of the circuit breaker does not have an overcurrent release, and the N pole is always on, and is not disconnected with the other three phase poles;
3, the circuit breaker N pole with overcurrent release, N pole and the other three phase line together with the circuit;
4. The N-pole of the circuit breaker has an overcurrent release, and the N pole is always on, and is not disconnected with the other three phase poles;
5. The N-pole of the circuit breaker is equipped with a neutral line breakage protector, and the N pole is combined with the other three phase lines to form a circuit;
6. The N-pole of the circuit breaker is equipped with a neutral line breakage protector. The N pole is always on and is not disconnected from the other three phase poles.
Types 1 and 2 are suitable for normal conditions where the neutral current does not exceed 25% of the phase current (transformer junction group is labeled Yyno), where type 2 is for the TN_C system (PEN line is not allowed to open); 3 and 4 types Applicable to three-phase load unbalance, and there are a large number of electronic devices in the load (very large harmonic components), resulting in N line current equal to or greater than the phase line current, N line overload and unable to withstand overcurrent tripping of three phase lines The action of the device to cut off the overload fault; Type 4 is suitable for the TN_C system; Types 5 and 6 are suitable for cutting the three-phase and neutral lines when the neutral line is disconnected to protect the single-phase equipment from damage and electrical contact accidents. The type is suitable for the TN_C system.
About the application of four-pole circuit breakers:
At present, there is no requirement for hard use of national standards or regulations in China. Although the design specifications for regional four-pole electrical appliances (circuit breakers) have been introduced, the debate about installing and not installing quadrupole appliances is still in progress. In recent years, the use of some areas has shown a trend of beekeeping, and various circuit breaker manufacturers have also designed and manufactured various types of four-pole circuit breakers to be put on the market. The author agrees with one opinion, that is, whether or not it is necessary to ensure the reliability and safety of the power supply, so it is basically:
(1) TN-C system. In the TN-C system, the N line and the protection line PE are combined into one (PEN line). Considering safety, the PEN line is not allowed to be disconnected at any time, so the four-pole circuit breaker is absolutely disabled.
(2) Four-pole circuit breakers can be used in the TT system, TN-CS system and TN-S system to ensure the safety of the maintenance personnel during maintenance, but the N-poles of the circuit breaker can only be connected to the TN-CS and TN-S systems. N line, but not PEN or PE line;
(3) Where the dual power supply is installed, since all neutral lines (N lines) in the system are connected, in order to ensure the safety of the switched power switch (circuit breaker), a four-pole circuit breaker must be used;
(4) For the single-phase main switch entering the house, a two-pole circuit breaker with N pole should be used (for the isolator during maintenance);
(5) Residual current protector (leakage circuit breaker) for 380/220V system, the neutral line must pass through the zero-sequence current transformer (core) of the protector to prevent the passage of the neutral line, so that the load of 220V If there is leakage current and malfunction, use a quadrupole or a two-pole residual current protector with a neutral line.
Withstand high voltage up to 750V (IEC/EN standard)
UL 94V-2 or UL 94V-0 flame retardant housing
Anti-falling screws
Optional wire protection
1~12 poles, dividable as requested
960 Series Terminal Blocks,Electrical Terminal Strips,Electronic Terminal Blocks,Nylon Terminal Block,ballast terminal blocks
Jiangmen Krealux Electrical Appliances Co.,Ltd. , https://www.krealux-online.com