Debugging process of distribution cabinet in Thailand

The debugging process of distribution cabinets in Thailand is similar to the international general standards and practices in other countries, and generally includes the following steps:

Preparation before commissioning

Data inspection: check whether the installation drawings, wiring diagrams, equipment lists, product manuals and other data of the distribution cabinet are complete, and ensure that the debugging personnel are familiar with the drawings and technical requirements.

Preparation of tools and instruments: Prepare tools needed for debugging, such as multimeter, megger, phase sequence meter, grounding resistance tester, etc., and ensure that the instruments are calibrated and within the validity period.

Qualification confirmation of personnel: Debuggers should have corresponding electrician qualifications and professional skills, and be familiar with the debugging process and safety specifications of power distribution cabinets.

Appearance and installation inspection: check whether the appearance of the power distribution cabinet is damaged or deformed, whether the door switch is flexible and whether the door lock is normal. Confirm whether the installation of the power distribution cabinet is firm, whether the foundation is horizontal, and whether the verticality and levelness of the cabinet meet the requirements. Check whether the installation of electrical components in the cabinet is firm, whether there is looseness or damage, and whether the model and specification of components are in line with the design.

Wiring inspection: check whether the wiring of the primary circuit and the secondary circuit in the cabinet is correct, whether the terminals are fastened, whether there is missing or wrong connection, and whether the specifications and colors of the wires meet the requirements according to the wiring diagram.

Debugging content

Insulation resistance test: measure the insulation resistance between the main circuit, control circuit, signal circuit and other parts and to the ground with a megger. Generally, the insulation resistance of the main circuit should not be less than 10MΩ, and the insulation resistance of the control circuit and signal circuit should not be less than 1MΩ.

Grounding resistance test: measure the grounding resistance of the distribution cabinet with a grounding resistance tester. The grounding resistance should meet the design requirements, generally not more than 4Ω.

Debugging of switchgear: Manually operate circuit breakers, disconnectors, load switches, etc., and check whether their opening and closing actions are flexible and reliable, whether the actions of auxiliary contacts are correct, and whether the cooperation with main contacts is good. Testing the parameters such as closing time, opening time and synchronism of the circuit breaker should meet the technical requirements of the product.

Debugging of protection device: simulate overload, short circuit, undervoltage, overvoltage and other faults, and check whether the protection device can act accurately and whether the action time is within the specified range. For selective protection devices, it is necessary to carry out inter-stage coordination debugging to ensure the selectivity and reliability of protection actions.

Debugging of control loop: Turn on the control power supply, and check whether the control elements such as control buttons, indicator lights and relays operate normally and whether the signal indication is correct. Debug the electrical interlock and mechanical interlock to ensure that the interlock relationship between electrical components meets the design requirements and prevent misoperation.

Debugging of measuring instruments: Check whether the instructions of measuring instruments such as voltmeter, ammeter and power meter are accurate, which can be verified by introducing standard signals or comparing with other accurate instruments. For the distribution cabinet equipped with current transformer and voltage transformer, check whether the transformer ratio is correct and the polarity is consistent.

Phase sequence check: use the phase sequence table to check whether the phase sequence of the power supply is correct, and ensure that the input phase sequence of the power distribution cabinet is consistent with the phase sequence required by the load.

Power-on test: After completing the above debugging, connect the power distribution cabinet to the power supply and conduct no-load power-on test. Observe the operation of electrical components in the power distribution cabinet, check whether there is abnormal sound, fever, ignition and other phenomena, and measure whether the voltage and current of each phase are normal.

load test

Light load test: after normal no-load operation, gradually put part of the load into operation, check the operation status of the distribution cabinet under light load, measure parameters such as voltage, current and power, and check whether the temperature rise of all electrical components is normal and the protection device is reliable.

Full-load test: gradually increase the load to the rated load and keep running for a period of time, observe the operation of the distribution cabinet, check the heating of all electrical components and lines, measure whether the parameters are within the allowable range and whether the protection device can operate within the specified time.

Overload test: On the basis of full-load test, appropriately increase the load to overload state, check whether the protection device can act in time and cut off the circuit to protect the safety of equipment and lines.

Debugging result record and report

Record content: record the test data, test results, problems found and treatment in the debugging process in detail, including insulation resistance value, grounding resistance value, switching device action time, protection device action value, error of measuring instrument, etc.

Report preparation: according to the debugging records, prepare the debugging report, which should include debugging items, debugging methods, debugging results, existing problems and suggestions, etc. The debugging report should be signed by the debugging personnel and auditors for confirmation.