102
Capacity
controller RS8GG602 © Danfoss 2015-03
AK-PC 781
Load shedding
On some installations there is the desire to limit the cut-in com-
pressor capacity so that one can limit the total electrical load in
the store for periods.
This limitation can be activated in the following way:
• Via signal from the network
• Via signal on one DI input + signal via the network
• Via signal on two DI signal via the network
The signal via the network will result in the same function as if the
signal were received on DI 1.
For each digital inlet a limit value is attached for the maximum
allowable cut-in compressor capacity so that one can carry out the
capacity limitation in 2 steps.
When a digital inlet is activated, the maximum allowable compres-
sor capacity is limited to the set limit. This means that if the actual
compressor capacity upon activation of the digital inlet is higher
than this limit, then so much compressor capacity is cut-out that
it will then be on or under the set maximum limit value for this
digital inlet.
The threshold value may not be set lower than the compressor's
lowest capacity step/"Start speed".
When both load-shedding signals are active, the lowest limit value
for the capacity will be the one that is applicable.
Max. time
A max. period with low compressor capacity can be set. When the
period expires, the system switches to normal regulation until the
suction pressure is once again in place. Load shedding will then
be permitted.
Overriding of load shedding:
To avoid load shedding leading to temperature problems for the
chilled products, an overriding function is fitted.
A overriding limit is set for the suction pressure as well as a delay
time for each digital inlet.
If the suction pressure during load shedding exceeds the set P0
overriding limit and the attached delay times for the two digital
inlets expire then load shedding overrides the signals so that the
compressor capacity can be increased until the suction pressure
is again under the normal reference value. The load shedding can
then be activated again.
Alarm:
When a load shedding digital inlet is activated, an alarm will be
activated to inform that the normal control has been bypassed.
This alarm can however be suppressed if so desired.
Summary of Contents for ADAP-KOOL AK-PC 781
Page 31: ...AK PC 781 Capacity controller RS8GG602 Danfoss 2015 03 31 ...
Page 41: ...AK PC 781 Capacity controller RS8GG602 Danfoss 2015 03 41 Example continued ...
Page 44: ...44 Capacity controller RS8GG602 Danfoss 2015 03 AK PC 781 ...
Page 135: ...AK PC 781 Capacity controller RS8GG602 Danfoss 2015 03 135 ...
