How to debug and accept the distribution cabinet in Vietnam after installation?

debug phase

Insulation resistance test

Objective: To check the insulation performance of the power distribution cabinet, and ensure that the electrical equipment and lines will not have potential safety hazards such as leakage under normal operation and fault conditions.

Methods: Using the insulation resistance tester, the insulation resistance of busbar, switch, contactor and other electrical equipment in the distribution cabinet was tested. The test voltage is usually selected according to the rated voltage of the distribution cabinet. For example, for the distribution cabinet with rated voltage below 1kV, a 1000V insulation resistance tester is used. The insulation resistance value shall conform to the relevant electrical standards of Vietnam, and it is generally required to be not less than 0.5MΩ (megaohms).

Grounding resistance test

Objective: To verify the effectiveness of the grounding system, and to ensure that current can be quickly introduced into the earth when electrical equipment fails, such as leakage, to ensure the safety of personnel and equipment.

Methods: Using a grounding resistance tester, the current electrode and voltage electrode of the tester were inserted into the ground according to the specified distance, and the resistance between the grounding device of the distribution cabinet and the earth was measured. In Vietnam, the grounding resistance is generally required not to exceed 4Ω (ohm). If the grounding resistance does not meet the requirements, it is necessary to check the number, depth and connection of grounding electrodes, and increase grounding electrodes or improve soil resistivity around grounding electrodes if necessary.

Power on test

Objective: To check the working conditions of electrical components in the power distribution cabinet, including whether the voltage and current are normal and whether the indicator light is displayed correctly.

Methods: After ensuring that the insulation resistance and grounding resistance are qualified, power on the distribution cabinet step by step. First, turn on the main switch and observe whether the reading of the voltmeter is within the rated voltage range. Generally, the allowable deviation is 5%-10% of the rated voltage. Then turn on the switches of each branch in turn, and use the clamp ammeter to check whether the current of each branch is normal, whether the actions of all electrical equipment (such as contactors, relays, etc.) are accurate, and whether the corresponding indicator lights up. For distribution cabinets with control circuits, it is also necessary to check whether the input and output of control signals are correct, such as checking the pull-in and release of relays through analog signal input.

functional test

Objective: To verify whether the functions of the power distribution cabinet, such as overload protection, short circuit protection and undervoltage protection, are normal.

Method:

Overload protection test: by adjusting the load current, it will exceed the set overload current value of protection devices (such as thermal relays) in the distribution cabinet. Observe whether the protection device can act within the specified time and cut off the circuit. For example, for a general thermal relay, when the overload is 1.2 times the rated current, the action time should be within 2 hours.

Short-circuit protection test: use special short-circuit test equipment or simulate short-circuit situation to short-circuit the circuit instantly. Check whether the fuse or circuit breaker in the distribution cabinet can quickly cut off the short-circuit current, and the action time should be within the specified short-circuit protection action time range, which is generally tens of milliseconds to hundreds of milliseconds.

Under-voltage protection test: adjust the power supply voltage to make it lower than the set value of the under-voltage protection device in the distribution cabinet. Observe whether the undervoltage protection device can act in time and cut off the circuit to protect the electrical equipment from undervoltage damage.

acceptance phase

observational check

Check the overall appearance of the power distribution cabinet, including whether the surface of the cabinet is flat, free from deformation and scratches, whether the door is flexible to open and close, and whether the door lock works normally.

Check whether the signs on the power distribution cabinet are clear and accurate, including the names, numbers, uses and warning signs of electrical components, so as to ensure that the operators can easily identify and operate them.

Check whether the wiring of the power distribution cabinet is neat and beautiful, whether the identification of cables is clear, and whether cables with different voltage levels and different uses are laid separately to avoid crossing and confusion.

Document inspection

Check whether the installation documents of the power distribution cabinet, including design drawings, installation instructions, product certificates, test reports and debugging records of electrical equipment, are complete. These documents are an important basis for the quality and installation of distribution cabinets, and are also important reference materials for future maintenance and management.

Check whether the parameters and indicators in the document are consistent with the actually installed distribution cabinet, such as the model, specification and rated parameters of electrical equipment.

Performance acceptance

Check the electrical performance of the distribution cabinet, including whether the parameters such as voltage, current and power factor meet the design requirements. It is verified by looking at the test records in the debugging stage and the actual measurement on site.

Check the protection performance of the distribution cabinet, and check whether the functions such as overload protection, short circuit protection and undervoltage protection have been tested and acted reliably, and whether the protection action time and value meet the design specifications and relevant Vietnamese standards.

Check the operation stability of the power distribution cabinet, and check whether there is abnormal heat, noise and vibration of the electrical equipment after continuous power-on operation for a period of time (for example, 24-48 hours) to ensure the stable operation of the power distribution cabinet.