GE 7FA.05 - AC Motors; Couplings; Unit Piping Systems; Fuel, Oil, Water and Air

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GEK 116862 Inspection and Maintenance Instructions for 7FA.05 Gas Only and Dual Fuel Gas Turbines

Check operation and timing of the staged resistance starting system. A high speed chart recorder and

DC current probe (or equivalent equipment) are required to perform these checks. Motor current

should not exceed 5 times nameplate current or 66% of circuit breaker trip settings. The motor should

reach operating speed as fast as possible without violating these requirements. The staged contactor

drop out times should not vary from drawing by more than 0.5 seconds.

B. AC Motors

Examine the collector rings, brushes, brush holders and studs for cleanliness and wear. Collector

rings should maintain their polished surface. Brushes should move freely within their holders, but set

firmly in contact with the collector rings. Be sure the pigtail conductors are securely fastened to the

brush holders. Check the insulation for cleanliness and wear.

Periodic greasing of some motors required. See manual for specific greasing instructions. Check

motor insulation resistance and verify functionality of motor heaters if applicable.

Check the vibration of the motor while it is coupled to the pump. The vibration should not exceed 3

mils (0.08 m). Check the cooling passages and louvers of the motor to make sure they are clean,

undamaged and unobstructed.

VII. COUPLINGS

Inspect couplings between motors and/or between motors and pumps for deterioration, missing or loose

hardware and cleanliness. Refer to the Operation and Maintenance Manual under systems for further

information.

VIII. UNIT PIPING SYSTEMS

A. Fuel, Oil, Water and Air

A walk around visual inspection should be made to check piping systems for leaks, loose hardware,

loose hangers, leaky gaskets, valve packing leaks, vibration of piping, vents functioning and a general

check for security of the systems. Corrective action should be taken to correct any abnormalities

found.

B. Flexible Metal Hoses (FMH)

The exterior of the FMH and the flange faces should be observed for any obvious signs of wear or

damage. For FMH that have an external armor covering, small nicks and dings may be acceptable

provided the armor is not against the internal braids. However, signs of rubbing or holes in the armor

should be investigated further.

For FMH without armor, the exterior of the braid should be carefully observed for any signs of

damage or wear. Signs of damage to the armor or braids should result in the FMH being replaced.