RING-PISTON 3445153 - Caterpillar

Initial Start-Up
Preparing a generator for parallel operation requires special attention. Before you attempt to parallel units for the first time, check all the units for the following three conditions:
Same phase rotation
Same alternating current frequency
Same voltage adjustment
Check the phase rotation.The paralleled units must have the same phase rotation. There are two methods that are used to determine if the paralleled units have the same phase rotation. These methods are listed below:
Use a phase rotation meter to check the phase rotation.
Use a set of three light bulbs to check the phase rotation.The method for determining the phase rotation with three light bulbs is described below.
Illustration 1 g00695380
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.
Connect the light bulbs with rated voltage between the generator leads and the corresponding line phase. For example, connect terminal 1 to line 1 across the open circuit breaker.
Start the units and bring the 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. In order to correct the problem, stop the units. Remove generator leads 1 and 3 at the circuit breaker. Exchange these generator leads. This exchange reverses the direction of phase rotation. Terminal 2 should always be connected to line 2.
If the lights blink in unison, the generators have the same phase rotation. The first condition of the Initial Start-Up has been met.
Adjust the frequency.The paralleled unit must operate at the same speed. Speed is proportional to the alternating current frequency.
Allow each electric set to run under load for about 30 minutes.
Adjust the governor control so that the unit provides the rated frequency at full load.
Remove the load and check the high idle speed. The high idle speed should be approximately 2 to 5 percent above full load speed for governors that are equipped with droop. If these speeds cannot be obtained, contact your Caterpillar dealer.
For the most consistent results, repeat 2.b and 2.c until the second condition of the Initial Start-Up has been met.
Adjust the voltage.There are two different methods for reactive power equalization:
Reactive droop compensation (Individual compensation)
Cross current compensation (Differential compensation)With reactive droop compensation, the voltage regulator causes an individual generator output voltage to change in proportion to the reactive current. The reactive current is measured with a current transformer (CT).The reactive current can be either lagging or leading. As the lagging reactive current flow increases, the voltage regulator will cause the generator output voltage to droop (lower) proportionally. As the leading reactive current increases, the voltage regulator will cause the generator output voltage to rise proportionally.This method will tend to reduce the reactive current. This method also provides better sharing of KVAR with other units. The reactive droop compensation is a standard method on the Cat generator sets. The procedure that is provided below for adjusting the voltage