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| Illustration 1 | g00779093 |
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Voltage Droop Control (Typical Example) (1) Voltage droop transformer T1 (2) Lead (3) Main stator (4) VR6 voltage regulator | |
There are two primary requirements for parallel operation:
- Genset engines should share the real power requirements (kW) of the electrical load.
- Generators should share the reactive power requirements (kVAR) of the electrical load.
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| Illustration 2 | g01021519 |
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The Cat VR6 presents an electrical shock/electrocution hazard. This hazard will cause serious injury or death. Service by trained personnel only. The terminals and heat sinks are live at hazardous voltages when power is applied and for up to 8 minutes after power is removed. |
The engine governors will control sharing of the real power requirements (kW). The voltage regulator will control sharing of the reactive power requirements (KVAR) of the total system load. Occasionally, one generator output voltage may be slightly higher than the output voltage other generators. This will supply lagging reactive current flow to the other generators that are connected in the group. The lagging reactive current flow will circulate between generators. This could possibly cause current overloading.
In order to share reactive loads, an individual generator output voltage droops in proportion to the lagging reactive current flow. The reactive current flow is measured with a current transformer (CT). As reactive generator output current increases, the regulator will cause the output voltage to lower proportionally. If the measured reactive current is leading, the output voltage will rise. In either case, this action will tend to reduce the reactive current for better sharing of kVAR with other units.
The following items are required in order to provide the voltage droop function:
- Droop CT - 1 Ampere CT or 5 Ampere CT (1)
- wiring harness
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| Illustration 3 | g01021519 |
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The Cat VR6 presents an electrical shock/electrocution hazard. This hazard will cause serious injury or death. Service by trained personnel only. The terminals and heat sinks are live at hazardous voltages when power is applied and for up to 8 minutes after power is removed. |
The droop CT senses load current in lead "T2" (2) of 4/6 lead generators or in lead "T8" of 10/12 lead generators. The droop adjustment adjusts the droop voltage. The droop CT may be standard on some generators or an attachment on other generators. The wiring harness may be standard on some generators or an attachment on other generators.
Note: At full rated current (1 Ampere or 5 Ampere), the droop adjustment is up to 10%. As the CT current decreases, the amount of droop adjustment decreases proportionally. It is important to size the CT correctly for the load which will be carried by the generator.