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3. Offset and regulation of the gas cooler and pump
(max. heat recovery)
Reference
Regulation is done using a heat exchanger temperature/receiver
temperature of e.g. 40°C, the value is adjustable. A temperature
sensor Shr is installed in the receiver, and the pump speed is
controlled so that the temperature is kept to the set value.
The controller does not start until a signal has been received from
the external controller and the signal has started the pump.
Regulation
The following can be used as a regulation sensor:
- Shr8
- Shr4
- Delta T via heat exchanger (Shr4-Shr3) of e.g. 4K.
The pump can be controlled on/off or variably (recommended).
For Shr4 or Delta T regulation it must be controlled variably.
During variable operation the pump will stop when the regulation
require a lower capacity than the selected min. speed capacity
for the pump.
Increasing the condensation pressure
The external controller will emit a signal between 0 and 10 V
(0-5 V), which the controller will use to start the following
functions in order to achieve maximum heat recovery:
1. Signal on DI input for heat recovery is received
2. The pressure Pgc is increased to Pgc HR min.
3. The external voltage signal is registered (the higher the value,
the greater the need for heat).
The signal must be a 0-10 V signal or a 0-5 V signal. The signal is
converted by the controller to 0-100% capacity and will have the
following impact:
a. Control of the pump
The pump is released to operation. The valve is coupled up.
b. Pressure increase
The pressure is measured using the pressure transmitter Pgc
and the controller at the valve Vhp. If necessary, the pressure
will be kept at a value between Pgc HR min. and Pg HR offset.
c. Fan control
The fan's capacity is tuned down so the temperature is
increased. The temperature is measured with Sgc.
If necessary, the temperature reference will not be increased
118
Capacity controller RS8GG602 © Danfoss 2015-03
to the value Max. Cond. Ref. Offset. At this value, the fans will
stop completely.
d. Disconnect the gas cooler
The valve V3gc routes the gas outside the gas cooler and the
sensor Shp now registers the temperature instead of Sgc.
(If the controller has had the gas cooler disconnected, a timer
function will start when the system switches over once again
to gas cooler operation. The timer function will keep the
regulation in gas cooler mode for 3,600 seconds, until a
disconnection is permitted again.)
The "Heat recovery status" picture shows the current regulation
status.
When the pump is running, the
V3hr valve will couple to the heat
exchanger.
The values for the various capacity points are adjustable.
Up to 5 signals can be received from external regulations. The
controller will use the signal that requires the most capacity.
The signal employed is filtered over a time period. The length of
the period can be set.
Relay output
A relay can be reserved that will pull in if the received signal ex-
ceeds 9.5 V (4.75 V) for more than 10 minutes.
The relay is defined in the function: "Additional heat output".
AK-PC 781
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