SWITCH 7N5946 - Caterpillar

Initial Startup Requirements
Preparing a generator for parallel operation requires special attention. Before attempting to parallel units for the first time, all units must be checked. The following three conditions must be met:
Same phase rotation
Same alternating current frequency
Same voltage adjustmentPhase Rotation
The phase sequence of the generator must be equal to the phase sequence of the system in order for the systems to operate in parallel. The phase sequence can be checked by a phase rotation meter. Check the phase sequence at the generator and check the phase sequence at the lines that come from the system bus. Synchronizing lamps can also be used in order to determine the relative phase sequence. The correct phase sequence is indicated when the brilliance of the two lamps changes together.
Illustration 1 g00630590
Phase Rotation Meter (Using Three Light Bulbs)
Personal injury or death can result from high voltage.When power generation equipment must be in operation to make tests and/or adjustments, high voltage and current are present.Improper test equipment can fail and present a high voltage shock hazard to its user.Make sure the testing equipment is designed for and correctly operated for high voltage and current tests being made.When servicing or repairing electric power generation equipment:
Make sure the unit is off-line (disconnected from utility and/or other generators power service) , and either locked out or tagged DO NOT OPERATE.
Remove all fuses.
Make sure the generator engine is stopped.
Make sure all batteries are disconnected.
Make sure all capacitors are discharged.Failure to do so could result in personal injury or death. Make sure residual voltage in the rotor, stator and the generator is discharged.
Connect the light bulbs between the generator leads and the corresponding line phase. Ensure that the light bulbs are the correct rated voltage. Refer to Illustration 1.
Start the parallel units. Bring these units up to speed. As the units approach the same speed, the lights will start to blink.
If the lights blink in sequence, one of the units is connected backward. If one of the units is connected backward, remove generator leads "1" and "3" at the circuit breaker. Exchange generator leads "1" and "3". This reverses the direction of the phase rotation. Line "2" should always be connected to line "2".
If lights blink in unison, the phase rotation of both generators is equal.
Illustration 2 g00633434
Synchronizing Lights Module
The Synchronizing Lights Module is equipped with a reverse power relay. This will provide additional protection to the system. If the engine should lose power, the other parallel units will attempt to motorize the engine and the generator. Power will flow to the failing generator. This power will cause the failing generator to act as a motor. When this occurs, the reverse power relay will activate. The failing engine and the generator will be shutdown. For additional information, refer to the appropriate EMCP II Service Manual Module.Frequency Adjustment
The speed of the paralleled units must be equal. Speed is proportional to the alternating current frequency.
Allow each electric set to run under load (about 30 minutes).
Remove the load and check the high idle