Monday, December 28, 2009

Electrical generator site tests

Upon completion of the site installation work for the standby electrical generator, the generator should be tested again to ensure that it is working properly. There are always some possibilities that some damages have occurred to the electrical generator during transporting process including loading and unloading. Also some damages may have happened during the storage at the construction site and during the installation work itself.

The following tests need to be carried on the permanent installation of the unit. The manufacturer of the generator should send their representative to do the tests. A report recording each item of the testing shall be certified by the manufacturer and submitted to the Engineer.

All calculations to derive performance data shall be made strictly in accordance with formulae given in the relevant standards. Any alterations or deviations from the relevant standard test layout or formula shall be subject to the prior approval of the Engineer.

The formulae used for correcting test results to site conditions shall be subjected to the Engineer's approval and be given with the test results together with calibration details of any measuring instruments.

A. Diesel Engine

a. The set shall be started and run from cold in the presence of the Engineer and loaded to its full load shop rating in the minimum time stated in the Schedule of Technical Data.

b. Thereafter the engine shall be kept at 50% of the full load (FL) current and 85% FL for 11/2 hours each, and then at its full rated output continuously for a period of 5 hours followed by a 10% overload run of 1 hour duration.

c. The following functional cheeks shall be undertaken during the tests, including but not limited to:-

1. The ability of the starting system to perform in accordance with the specified requirements.

2. Uninterrupted continuous operation at the loads stated earlier.

3. The correct functioning of the over speed safety devices.

4. The ability of malfunction protection and warning devices to respond correctly to the fault conditions under which they should operate. For example, low lubricating oil pressure, high lubricating oil temperatures, high coolant temperatures, etc.

5. The dynamic and steady characteristics of the governing system in accordance with BS 5515. This shall include the full load rejection test, speed droop test at 20% load reducing from full load to zero load and over speed test.
6. The functioning of all automatic pressure and temperature control.

B. Engine inspection after tests

The Engineer reserves the right to request the Sub- Contractor to strip the engine for examination and selected parts for inspection without cleaning and exactly as taken from the engine. Any part examined by the Engineer and deemed needing replacement shall be replaced by the Contractor without any additional cost.

C. Leak test

The storage tanks shall be subjected to a test pressure of 0.66 bar ( 10 psi ) for a period of 1 hour on site to the approval of the Engineer. Compressed air or dry nitrogen may be used for the pressure test. It is not permissible to use water for on-site testing.

All piping after installation shall also be pressure tested to 15 bars for a period of one hour during which the leakage shall be zero.

D. Alternator

a. Visual inspection


Terminal marking, rating plate and danger signs.

Finishes, lifting lugs, etc.

Mounting of engine and generator set.

Cabling system.

Earthing and terminating arrangement.

Lubrication system

Sleeve bearings (where applicable).

b. Dielectric test

c. Insulation resistance test.

d. Functional (Sequence) Test

Operation of AVR

Operation of neutral earthing switches.

Operation of all indicating and metering devices.

Operation of all alarm devices.

e. Noise level measurement

f. Angular velocity (rpm) check

g. Phase rotation check

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