Load sharing relay
with reverse power relay and over load protection
LOAD BALANCE RELAY
As the demand for the Electric Power is increasing day by day it calls for a efficient Power Generation and Distribution. To get good
Efficiency the Power is Generated depending upon the demand. This achieved by having more numbers Generators of Lower capacity than having one high Capacity
Generator. Depending on the requirement of the Load the number of Generators are added or removed. To achieve this it requires a Load sensing Device, Auto
Synchronizing device, Active and reactive load sharing Relay. The active load sharing is achieved by a load sharing relay and reactive load sharing by a PF Relay or KVAR sharing relay.
This unit is used for Automatic load balance between gensets in Parallel
Operation. A proportional regulation of the nominal regulation of the nominal value for several generating set's in
parallel can be effected.
The active power is sensed by sensing the voltage and current of the same phase. The voltage and current are vectorially multiplied to get a
DC. signal proportional to the Load. This DC signal is compared with a DC signal of the other DG/TG sets and a linear signal 0-10V DC or 4-20MA or potential free pulsating signal will be given to take the proportional load. While operating in sole mode no adjustments are required.
This unit also sense the frequency of the generator and give the pulsating signal to rise or lower the speed to get the required / Set frequency. THIS Signal will control the frequency when the set is working on sole mode. This will maintain the frequency of the alternator irrespective of the load.
While functioning with grid a DC signal is derived which is proportional to the load. This DC signal is compared with the reference and error signal is amplified and given to pulsating circuit. Here a rising pulse signal will be given when ever the load taken by the TG/DG is less that the set value or a lowering signal will be given if the load on the alternator is more than the set value.
This circuit also gives a signal directly to incorporate with governor circuit
by a signal and 2 to 10V DC or 4 to 20MA. Here also signal of high voltage is applied to governor if the load is less than the set value and low voltage for load more that the set value. In this circuit a provision is given to set the no load speed (i.e., a governor voltage can be set for a required frequency.
For DG set operating in parallel a synchronizing signal is derived form each load sharing relay and applied to a common bus. THE load taken by each Alternator is compared with bus signal and correct the respective governor. Thus each Alternator is loaded proportional to their rating.
In addition to load sharing this unit is also having a in-built reverse power sensing circuit. This circuit sense the reverse power and compare with set reverse power and a electro magnet relay will pick up after a set time. THE contact of the relay can be used for
alarm or to a tripping circuit. Thus, protecting the DG/TG set form reverse power.
This relay also sense the load of TG/DG set and compare with set load signal and a electro magnet relay will pickup after a set time delay. The contact of the circuit can be used for alarm or tripping the DG/TG set. Thus, protecting the DG/TG set form over load.
