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How to choose a four-pole circuit breaker in 2020?

By:Nader Updated:September 08,2020 18:25PM

Phase four-wire (0.4 / 0.23KV) power system selection principle of four-pole switch:

1. Switch between a normal power supply and a backup generator application four-pole switch.  

2. Residual current protection with dual power switch should quadrupole switch. Grounding power switch in the same system, two converters with a residual current operated protective switch its children should quadrupole.

3. Between two different power switch grounding system should use four-pole switch.

4. TN-C system non quadrupole switch.

5. To ensure the functionality of power conversion switching device must be applied to all live wire, and must be possible to make these power supplies in parallel, unless the device is specially designed for this scenario. In the case of total equipotential case, TN-S, TN-C-S system generally do not need four-pole switch is provided.

6. TT power line switching system should be four switches.

7. IT system should be neutral line when quadrupole switch.

4P breaker four types:

1. N pole overcurrent release device is not installed, always on the N-pole and the N pole is not engaged with the other three poles points;

2. N pole overcurrent release device is not installed, the N pole and the other three taken together with pole points;

3. N mounting pole tripping element, and multiplexing the N pole with the other three poles;

4. N mounting pole tripping element, and an N-pole always on, no multiplexing system TN-C together with the other three poles NA leakage protection switch,

TN-C system N and PE is combined PEN line, the device housing when the leakage fault occurs on PEN line, leakage protection switch can not detect leakage faults.

5. pole GFCI for three-phase four occasions, as long as current flows through the unbalanced load will trip. In this case it must be used at the drain electrode of the switch 4 using 4PTN- TT- using 3PIT- selected using the following situations 3P

Selection guide for four-pole circuit breakers:

it is necessary to choose four poles circuit breaker:

1. with a dual power switching request system must selection of four poles circuit breaker, in order to meet the maintenance, when the maintenance of the required isolation and testing of the system;

2. single household residential switch should be used relative to the total two-pole switch with N poles (four poles circuit breaker available);

3. remaining current device (GFCI), must ensure that all the live conductors of the protected circuit is disconnected, therefore, the circuit having a residual current requirements, the choice should be with the N-pole earth leakage circuit breaker (e.g., quadrupole) of .Currently, domestic market supply quadrupole MCCB There are six types: 1, N pole circuit breaker without overcurrent release, N-pole and three-pole phase with the other multiplexing circuit; 2, circuit an N pole without overcurrent release, N-pole is always turned on, not with the other three-pole disconnection phase; 3, N-pole circuit breaker with overcurrent trip, the N pole and the other three phases polar together multiplexing circuit;.

4. N pole circuit breaker with overcurrent release, N-pole is always turned on, not with the other three-pole disconnection phase;.

5. N pole mounted circuit breaker neutral line break protectors, N-pole and three-pole phase with the other multiplexing circuit;

6. N-pole circuit breaker neutral line break protector is mounted, always on the N pole, and the other three-phase line is not pole disconnection together.

1 and type 2 is suitable for the neutral current does not exceed the normal current phase of 25 to 25% (reference group is transformer coupled Yyno), which applies to type 2 TN_C system (PEN line disconnection is not allowed); 3 and 4 pattern for three-phase unbalanced load and the load of a large number of electronic devices (a large harmonic component), resulting in the N line current is equal to or greater than the phase current, line N can not be overloaded by three phase overcurrent release the operation to cut the buckle device when overload fault; 4 are suited TN_C system; type 5 and 6 is adapted to break in neutral, cutting the three-phase single-phase and neutral in order to protect equipment from damage and the occurrence of indirect electric shock, type 6 is suitable for TN_C system.

Application of four-pole circuit breaker:

Currently not been able to make use of the provisions of mandatory requirements of national standards or regulations and the like, although the regional four-pole electrical (circuit breaker) design specifications have been introduced, but the installation does not install four Electric poles of the debate is still in progress, the trend rush of use in some areas appeared in recent years, each circuit breaker manufacturers have also design and manufacture various types of four-pole circuit breakers on the market. I agree with an opinion, is to use or not should be based on whether it can ensure the reliability of power supply, security prevail, and therefore generally:

1. TN-C system. TN-C system, N line and the combined protection of PE (PEN line), safety considerations, must not be interrupted at any time PEN line, it is absolutely disabled four poles circuit breaker;

2. TT system, TN-CS TN-S system, and the system may use four-pole circuit breaker, in order to guarantee maintenance overhaul'S security, but TN-CS and TN-S system, only N-pole circuit breakers connected to the N line, the line can not be connected PEN or PE;

3. dual power switching installation place, since all of the system of the line (line N) is Communications, in order to ensure that the switching of the power switch (breaker) security maintenance, four poles circuit breaker must be used;

4. into the single-phase main switch homes should be chosen with two poles N pole circuit breaker (used as an isolator overhaul)

5. for the residual current protection 380 / 220V system (leakage circuit breaker), the protector must cross the neutral line zero-sequence current transformer (core), to prevent without passing through the neutral line, the load of the 220V leakage current malfunction, this time should be used with a two-pole or four-pole residual current protector neutral line.