Home > Knowledge > Content

What are the test and regulation contents and power supply issues for LV switchgear?

Feb 20, 2017


Test and regulation contents and power supply issues for low voltage power distribution cabinets

Test and regulation contents

1. Tests on HV parts should be proceeded by departments which has permission from power supply department. Test standards should be assistant with national standard, requirements of local power supply department and products technical specifications.

2. Test contents:

HV switchgear frame, busbar, surge arrestor, HV porcelain, PT, CT and switches.

3. Regulation contents:

Regulation on overcurrent relay, time relay, signal relay and mechanical interlock.

4. Regulate secondary control wire and proceed imitation test, tight screws of all terminals again.

5. Insulation test:

Use 500V insulation resistance tester to test insulation at terminal plate of every circuit. Insulation resistance should be more than 0.5MΩ.

IR tester

6. If there is thyristors, integrated circuit, electronic components on secondary wire, use multimeter to test the circuit if it is switched.

7. Close temporary control power and operation power, remove the phase line at the upper side of fuses of control, operation power circuit, and connect with temporary power.

8. Imitation test

Proceed imitation test on control, operation, relay protection , signal action one by one which should be correct and normal and flexible.

imitation test1imitation test2

9. Remove temporary power and reset the removed lines.

Power supply conditions

1. All installation work should be completed, quality control(QC) department should check and all are qualified. There should have test reports.

2. Electroscopes, insulation shoes, insulation gloves, temporary grounding braided copper wire, insulation pads, foam fire extinguishers used for tests should be well prepared.

3. Check if there is left foreign matters on busbar and equipment.

4. Do well in trial running organization work and know directors, operators and supervisors clearly.

5. Clean the dust from equipment, power distribution room and control room. Use vacuum cleaner to clean electronic and instrument elements.

6. The action of relay protection should be flexible and reliable. The action of control, interlock and signal should be correct.

Power supply

1. After check by power supply department and all are qualified, close power to the building, electrify power and check phase and there is no error.

2. People from the installation department close the switch of incoming cabinet, check voltage of three phases of voltmeter on PT cabinet is normal.

3. Close switch of transformer cabinet and check if there is power.

4. Close incoming switch of LV switchgear and check voltage of three phases of voltmeter is normal.

5. Supply power one by one according to above sequences.




6. Proceed same-phase check at upper and lower side of switch( at open status) inside LV contact cabinet. Use voltmeter or 500V multimeter to test the same phase of two circuits by the two test needles. If there is no reading on voltmeter, the two circuits are with same phase. Test the other two phases with the same method.

7. Acceptance

Noload running for 24 hours. If there is no abnormality, conduct acceptance procedures for construction department. Supply change negotiation records, qualification records, specifications, test reports and other technical documents.