Wednesday, December 16, 2009

Switchboard electrical tests

The following electrical tests must be carried to all switchboards, sub-switchboards, main distribution boards and motor starter panels.

A. Full type tests
1) Full type tests shall be carried out in accordance with IEC 60439-1, IEC 60947-1, and IEC 60947-6-1. Certificates issued by approved independent testing laboratories shall be submitted to the Employer’s Representative.

The type tests shall include the following:
a) Verification of temperature-rise limits
b) Verification of the dielectric properties
c) Verification of the short-circuit withstand strength
d) Verification of the effectiveness of the prospective circuit
e) Verification of the clearances and creepage distances
f) Verification of mechanical operations
g) Verification of the degree of protection

B. Routine tests
Before the product leaves the works, the manufacturer shall carry out the relevant routine tests in accordance with IEC 60439-1 on the total assembly, and the IEC 60947-1 and IEC 60947-6-1 parts thereof when delivered with time intervals, and the results shall be recorded in a test report.

C. Special tests
Carry out the special tests recommended in IEC 1641 Guide for Testing Under Conditions of Arcing Due to Internal Fault, the result shall be recorded in a test report.

D. Acceptance Tests at Manufacturer’s Work
a) Acceptance tests shall be carried out on the completely assembled switchboards and motor starter panels. Transportable units can be wired together for the purpose of the tests instead of completing the busbar joints.

b) The tests and checks shall include, but not limited to, the following.

c) All the switchboards and motor starter panels shall be visually inspected for technical execution and conformity with the latest issue of approved drawings and the latest issue of the relevant standards. Spot checks shall be made to verify the following:

1) Dimensions
2) The degree of protection of enclosures
3) The degree of protection within compartments
4) The effectiveness and reliability of safety shutters, partitions and shrouds
5) The effectiveness and reliability of operating mechanisms, locks and interlock systems
6) The insulation of the busbar system
7) The creepage distances and clearances
8) The proper mounting of components
9) The internal wiring and cabling system
10) The correct wiring of main and auxiliary circuits
11) The suitability of clamping, earthing and terminating arrangements
12) The correct labeling of functional units
13) The completeness of the data on the nameplate
14) The availability of the earthing system throughout the switchgears
15) The interchangeability of electrically identical components

d) Dielectric tests shall be carried out in accordance with IEC 60439-1. The test voltage shall be at least:

1) For main circuits, 2500 Vac for 1 minute.
2) For control and auxiliary circuits, 2 x Un + 1000 Vac, with a minimum of 1500 Vac for 1 second.

e) Testing of the mechanical and electrical operation of a number of functional units on random basis, including their control and protective devices.

f) CT polarity, magnetization, ratio and burden measurements

g) Secondary injection tests

h) Primary injection tests

i) Painting and finishing tests:

1) Measurement of paint thickness.
2) Humidity (cyclic condensation) tests to BS 3900 Pt. F2. Painted panel shall withstand 1000 hours under test with no blistering of film and corrosion of base metal.
3) Adhesion test to ASTM D3359-02. Test tape shall not expose more than one 3 mm.sq of bare metal or underlying coating.
4) Impact resistance test to BS 3900 Pt. E7. Paint shall not chip off.

j) The manufacturer test shall be verified and witnessed by the Employer’s Representative or his representatives.


E. Site Tests
At the completion of the installation at site, each switchboard and motor starter panels shall be field tested by a representative of the manufacturer. A report recording each item of the tests shall be certified by the manufacturer and submitted to the Employer’s Representative.
a) Visual inspection
1) Correctness of location and mounting
2) Labeling, nameplates and markings.
3) Verification of torque for all nuts and bolts on busway.
4) Observation of cable bracing, both incoming and outgoing, certifying that it is in accordance with the manufacturer’s recommendations.
5) Safety shutters, partitions and shrouds.
6) Functional units, operating mechanisms, locks and interlock systems.
7) Mounting of components.
8) Internal wiring and cabling system.
9) Clamping, earthing and terminating arrangement.
10) Earthing system.

b) Dielectric tests shall be carried out in accordance with IEC 60439-1. The test voltages shall be at least:
1) For main circuits, 2500 Vac for 1 minute.
2) For control and auxiliary circuits, 2 x Un + 1000 Vac with a minimum of 1500V for 1 second.

c) Power frequency withstand voltage test.

d) CT polarity, magnetization, ratio and burden measurements.

e) Secondary injection test

f) Primary injection test

g) Functional / sequence test
i) Operation of each disconnecting means under load
ii) Operation of each automatic transfer switch
iii) Operation of all alarm devices

h) Mechanical operation test
i) Operation of each disconnecting means under load
ii) Operation of each auto transfer switch
iii) Operation of all interlocks

i) Calibration and setting of protection devices


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