How to wire the overvoltage and undervoltage protector

1、 Single phase circuit (220V) wiring
Applicable scenarios
Overvoltage and Undervoltage protection for household electricity and small single-phase equipment such as air conditioning and water pumps.
Wiring steps

(Note: Taking the common "upper inlet and lower outlet" type Protector as an example, the terminal identification is subject to the actual product)
Incoming end (power side)
L (live wire): Connect the power input live wire (red/brown wire) and insert it into the terminal labeled "L IN" or "1".
N (neutral wire): Connect the power supply incoming neutral wire (blue/black wire) and insert it into the terminal marked with "N IN" or "2".
Outgoing terminal (load side)
L (live wire): Connect the load live wire (such as the socket or lamp live wire end) and insert it into the terminal labeled "L OUT" or "3".
N (neutral wire): Connect the load neutral wire (blue/black wire) and insert it into the terminal labeled "N OUT" or "4".
Ground wire (PE)
If the protector has a grounding terminal (marked as "PE"), it is necessary to connect the ground wire (yellow green dual color wire) to the grounding bar of the Distribution Box, which cannot be omitted.
2、 Three phase circuit (380V) wiring
Applicable scenarios
Industrial equipment, three-phase motors, commercial distribution boxes, etc.
Wiring steps

image
(Taking the three-phase four wire system as an example, the protector is usually 4P or 3P+N type)
Incoming end (power side)
L1/L2/L3 (live wire): Connect the three-phase power supply incoming wire (yellow/green/red wire), and insert the corresponding terminals labeled "L1 IN", "L2 IN", and "L3 IN".
N (neutral wire): Connect the neutral wire (black/blue wire) of the three-phase power supply and insert it into the terminal marked "N IN" (if it is a 3P+N type).
Outgoing terminal (load side)
L1/L2/L3 (live wire): Connect three-phase loads (such as motors) and insert the corresponding terminals labeled "L1 OUT", "L2 OUT", and "L3 OUT".
N (neutral wire): Connect the load neutral wire (if any) and insert it into the terminal marked "N OUT" (independent of the incoming neutral wire).
Ground wire (PE)
Connect to the grounding terminal of the protector or the grounding strip of the distribution box to ensure the safe grounding of the equipment casing.
3、 Key precautions
Wiring direction and identification
Strictly follow the principle of "upward and downward" to avoid reverse connection causing protection function failure.
Confirm the terminal identification (such as "IN" for incoming wire and "OUT" for outgoing wire), and the neutral wire needs to be connected to the designated terminal (some protectors have fixed holes for the neutral wire and cannot be connected incorrectly).
Distinguishing between neutral and ground wires
Neutral wire (N): To participate in the working circuit, it needs to be connected from the protector terminal (single-phase connection is required, three-phase four wire system is required).
Grounding wire (PE): only used for safety grounding, must not be connected to the live/neutral wire terminals of the protector, and must be independently connected to the grounding system.
Load Matching
Ensure that the rated current of the protector (such as 16A/32A) is greater than the normal operating current of the load to avoid frequent misoperations.
Single phase equipment uses single-phase protectors (2P), while three-phase equipment uses three-phase protectors (3P/4P).
functional testing
After the wiring is completed, use a multimeter to measure whether the incoming voltage is normal (single-phase 220V ± 10%, three-phase 380V ± 10%) before closing.
After closing, simulate overvoltage (such as exceeding 264V) or undervoltage (such as below 176V) scenarios and observe whether the protector can trip within the set time (usually 0.1-1 second).
4、 Common errors and risks
Reversing the neutral and live wires may cause the protector to misjudge the voltage or fail to function properly.
Omitting ground wire: When the equipment casing leaks electricity, there is no protection and there is a risk of electric shock.
Out of range use: If a single-phase protector is connected to a three-phase circuit, it may burn out the equipment.
prompt
Non professionals are not allowed to operate high-voltage circuits! Complex scenarios (such as using in conjunction with residual current devices and circuit breakers) require an electrician to design a wiring scheme.
Some intelligent overvoltage and undervoltage protectors support remote monitoring and require additional signal lines to be connected. Communication wiring should be completed according to the instructions.