DIGITAL VOLTAGE REGULATOR (DVR A3) MODULE OPERATION - Continued
Loading and Stopping Profile
The loading and stopping profile (Figure 12) defines how the DVR will react to a reduction in frequency below the
knee frequency. A drop in frequency from the generator is usually due to one of two occurrences: either a heavy
load was applied which will take the generator a few seconds to recover from, or the engine driving the generator
is shutting down. In either case, the DVR reduces the generator output voltage. The reduction in voltage reduces
the power requirement of the load, thus allowing the engine to recover faster for a given increase in load.
The rate at which the DVR reduces the output voltage is called Decreasing V/Hz Slope 1 and is set to 3 V/Hz by
parameter :07. This rate is effective when the generator frequency is no more than 5 Hz below the knee
If the frequency drops below 5 Hz below the knee frequency, the generator set is assumed to be shutting down.
The DVR will reduce the output voltage further using a parameter called Decreasing V/Hz Slope 2, which is set to
2 V/Hz by parameter :08. This rate is effective until the generator gets to the minimum voltage setpoint
(parameter :09). This is the lowest voltage the DVR will attempt to regulate. The voltage will attempt to regulate
at this point until the frequency gets to the under frequency point (parameter: 10) at which point the voltage will
decrease to a minimum value.