PISTON 3825837 - Caterpillar

Starting Multiple Units
Use the procedure for starting single units in order to start multiple units. Refer to Operation Section, "Single Unit Operation".Paralleling Multiple Units
Units may be paralleled at no load. Units may also be paralleled with units under load. After the initial conditions for start-up are satisfied, verify for the following requirements:
One of the governors can be an isochronous governor. Electronic load sharing governors are an exception.
Generators must have voltage droop compensation or cross current compensation.
Start the unit which will be paralleled.
Turn on the synchronizer lights.
After the engine has run a few minutes, bring the engine up to synchronous speed. This means that the frequency of the incoming unit will be the same frequency as the unit that is on-line. The synchronizing lights will begin to blink. Note: The frequency of the incoming unit should be slightly greater than the line frequency. This will allow the incoming unit to assume some of the load instead of adding to the system load.
By using the governor control, adjust the engine speed until the lights blink very slowly.
The lights are off when the voltages of the two units are in-phase. At this point, very quickly close the breaker while the lights are out.
Use governor controls in order to share kW load between engines.
Generator temperature will be stabilized in approximately one hour. After the generator temperature has been stabilized, adjust the voltage droop rheostat of each generator. This will share the reactive load and this will limit the circulating currents. Less droop increases the reactive current that is carried by the generator. Adjusting the voltage droop rheostat in a counterclockwise direction will decrease the droop. Adjusting the voltage droop rheostat in a clockwise direction will increase droop. Load Division and Speed Droop (If Equipped)
Once two units have been paralleled, the unit's share of the kW load is determined by the governor control setting. If two units of the same capacity and the same governor characteristics have the same governor control settings, the units will share the load equally. The total load must not exceed the capacity of the one engine.In order to transfer the load from one engine to another engine, use the following procedure:
Increase the governor speed control of one unit in order to increase the load.
Reduce the governor speed control of the other unit in order to decrease the load on that unit.
Raise the governor speed control or lower the governor speed control of both units in order to change system frequency. Parallel Operation Of Governors
Illustration 2 g00630841
Load Sharing Module (Typical Example)
The generator set load sharing module provides either the droop load sharing or the isochronous load sharing for parallel applications. The load sharing module has a synchronizing parallel module SPM-A input. The module provides the proportional load sharing. More information is available in the System Operation, Testing and Adjusting, SENR6565, "Generator Set Load Sensor and Generator Load Sharing Module".Function of The Engine Governor
This section describes the function of the engine governor in relation to load division between parallel electric sets.It