Basler SR4A, Инструкция по эксплуатации, Страница: 13 / 43

2-3
(7) When a leading power factor (capacitive) load is applied to the generator, the voltage across R25
becomes out of the phase with the sensing voltage and the combined vectors of the two voltages
results in a smaller voltage being applied to the sensing rectifiers, then the regulator reacts by
increasing the generator voltage.
(8) When two generators are operating in parallel, if the field excitation on one generator should
become excessive and cause a circulating current to flow between generators, this current will
appear as a lagging power factor (inductive) load to the generator with excessive field current and a
leading power factor (capacitive) load to the other. The parallel Compensation circuit will cause the
voltage regulator to decrease the field excitation on the generator with the lagging power factor load,
and increase the field excitation on the generator with the leading power factor load, so as to
minimize the circulating currents between the generators.
b.
Reactive Droop compensation (Droop)
. This action and circuitry is called reactive droop com-
pensation (droop). It allows two or more paralleled generators to proportionally share inductive loads
by causing a decrease or droop in the generator system voltage.
c.
Reactive differential compensation (cross-current)
.
(1) Reactive differential compensation allows two or more paralleled generators to share inductive
reactive loads with no decrease or droop in the generator system output voltage. This is accom-
plished by the action and circuitry described previously for reactive droop compensation, and the
addition of cross connecting leads between the parallel CT secondaries as shown is Figure 3-4. By
connecting the finish of one parallel CT to the start of another, a closed series loop is formed, which
interconnects the CT's of all generators to be paralleled. The signals from the interconnected CT's
cancel each other when the line currents are proportional and in phase. No system voltage de-
crease occurs. These regulators provide the necessary circuit isolation so that parallel reactive
differential compensation can be used. The reactive differential circuit can only be used when all the
generators connected in parallel have identical paralleling circuits included in the loop.
(2) Reactive differential compensation cannot be used when paralleled with the utility or other infinite
(utility) bus. When reactive differential compensation is to be used on an isolated bus that may
parallel with the utility bus, an auxiliary contact on the breaker used to connect the isolated bus to the
utility bus must be used to open the reactive differential interconnecting loop any time the isolated
system is connected to the utility. Contact the factory for additional information.