EVC800i AUTOMATIC VOLTAGE REGULATOR
Specification, Installation & Adjustment Manual
10/02/2015
Page 3 of 9
V
oltage
37 38 39 40 41 42 43 44 45 46 47 48 49 50
Knee Point
Frequency
Under Frequency Roll Off [UFRO]
V/Hz slope [DIP] Adjustment
Dwell [DWELL] Adjustment
Droop [DROOP] Adjustment.
The AVR incorporation an under speed protection circuit for “Volts
per Hertz” characteristics when the generator speed falls below an
adjustable threshold. Under normal circumstance it would not be
necessary to adjust the factory setting of this control, but using
SW2, 47 or 57 Hz is quickly adjusted.
To re-adjust the UFRO knee point then proceed as follows:-
(It will be necessary to adjust the generator / engine speed during
this procedure)
1. Run the generator at no load and at nominal frequency (50 or
60 Hz)
2. Turn the UFRO control fully anti-clockwise (The red led should
be OFF)
3. Run the generator at required knee frequency (Typically 47 or 57 Hz)
4. Turn the UFRO clockwise until the led illuminates.
5. Return the UFRO control slowly anti-clockwise until the Led just turn off.
6. UFRO adjustment is now complete.
The DIP adjustment controls the amount of frequency related
voltage
dip. This feature is useful when the generator is coupled with the
turbo charged engines with limited step load acceptance capability.
This features only operate when the speed is below the UFRO
knee point and works by increasing the V/Hz slope to give greater
voltage dip in the proportion of falling speed. This also reduce KW
on the generator and helps recovering the falling speed.
With the DIP control fully anti-clockwise the generator voltage
characteristic will follow minimum V/Hz line as the frequency falls
below nominal. (1%Hz=1%V)
Turning the DIP clockwise creates a greater slope in the V/Hz
Characteristics thus aiding engine speed recovery.
The dwell function introduces a time delay between the recovery
of voltage and recovery of speed. The purpose of the time delay
is to reduce the generator KW below the available engine KW
during the recovery period, thus allowing the speed recovery.
Again this control is only functional below the “knee point”, i.e if
the speed stays above the knee point during load switching there
is no effect from the DWELL function setting. Thus function is
mostly used when the generator coupled to turbo charged
engines with limited block load acceptance.
When the DWELL control fully anti-clockwise the generator voltage
will follow the V/Hz line as per UFRO setting. Turning the DWELL
control increases the delay time between the speed recovery and
voltage recovery. The voltage recovery can be held back for several seconds using this switcher.
Generator intended for parallel operation are fitted with quadrature Droop current (CT) which provides a signal for AVR
allowing each generator to share reactive current. The CT is connected to S1 and S2 on the AVR. It is important to
match the generator no load voltage to within 1% of each other, to ensure good reactive load sharing. The Droop
adjustment is factory set to 0% so that during solo operation there is no voltage drop. With the control fully clockwise
is maximum Droop.
For synchronizing, Droop setting procedure is as below:-
1. Run the generator at 50% rated current at any power factor between 0.8 legging and 1.0, ensure that generator rated
current value gives a maximum rating for the frame size without any direct factor.
2. Adjust Droop control such that there is voltage drop of around 3 to 3.5% of the no load voltage.
3. Repeat above sets with the second generator also.
4. Now Droop adjustment is complete with both the set and can be synchronized.
V
oltage
37 38 39 40 41 42 43 44 45 46 47 48 49 50
Knee Point
1%Hz = 1%V
1%Hz = 3%V
V
oltage
Knee Point
Time