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What are the delivery test procedures of LV switchgear?

Jan 03, 2017

Delivery test procedures of Low voltage switchgear

1. The installation and layout of the elements should be consistent with drawing.

2. Check the wiring of main circuit and auxiliary circuit is correct and reliable and sectional area of leading wire meets the requirement of design.

3. Mechanical operation and power-on test: To verify the assembly and adjustment of the elements are well, operation is reliable(according to the design requirements and drawings).

(1) For withdrawable parts: Manual operation and motorized operation for WORKING position, TEST position and DISCONNECT position is flexible and reliable.

(2) To verify the stability and reliability of mechanical interlock.

(3) Functional test: imitate fault conditions during operation, verify the protection functions of protection circuits.

(4) The cabinet structure and elements should be free from deformation, performance changing after the above operation tests.

4. Verification of clearance and creepage distance: refer to international standard and technical standard.

(1) Caliper measurement should be consistent with the requirements of connected elements.

(2) Checking places include the places between electrified parts and no-power parts, the shortest distance between electrified parts.

(3) Bare interception parts of the main busburs not with the same phase or same polar inside the panel.

Verification table of clearance and creepage distance

Rated voltage(V)

Clearance(mm)

Creepage distance(mm)

Rated working   current

Rated working   current

≤63A

>63A

≤63A

>63A

≤60

3.0

5.0

3.0

5.0

60<V≤300

5.0

6.0

6.0

8.0

300<V≤500

8.0

10.0

10.0

12.0

5. Power frequency withstand test

When proceed power frequency withstand test to main circuit, make the other circuits not connected with main circuit to connect with metal frame, grounding.

Supply test voltage to:

(1) Between electrified parts and naked leading parts.

(2) Between each pole and all the other poles connected to the bare conductive parts of the complete set of equipment for this test

(3) The test voltage shall not exceed 50% of the value given in this article. Increase test voltage stably to the maximum value in a few seconds and keep for one second, and the test is qualified if there is no breakdown or discharge.

Test voltage value

Rated insulation   voltage UI

Dielectric   test voltage (AC root-mean-square value)

UI≤60

1000

60<UI≤300

2000

300<UI≤690

25000

690<UI≤800

3000

800<UI≤1000

35000

1000<UI≤1500*

3500

*Means DC

6. Use 500V meggar to measure insulation resistance.

Between the exposed conductive parts, the insulation resistance of each circuit grounding nominal voltage is at least 4 MΩ.

7. Protection circuit continuity test

The main grounding as a reference point, use ground resistance tester to test the insulation between frame from element installation place, instrument door and main grounding point, grounding resistance should be less than 0.1Ω, the selection of test points shall be more than 5 test points.