User Manual

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Siemens Universal controllers RMU710B, RMU720B, RMU730B CE1P3150en
Building Technologies Refrigeration demand 03.10.2011
26.4 Refrigeration demand relay (Q )
Release for an external refrigeration source, e.g., can be connected to this output.
The refrigeration demand relay responds as soon as the bus requests refrigeration.
Meaning:
 Contact open = No refrigeration demand
 Contact closed = Refrigeration demand
Main menu > Commissioning > Extra configuration > Aggregates > Refrigeration demand >
Operating line Adjustable values / remarks
Refrigeration demand
relay
---, N.Q1, N.Q3, ... / Activate output
Main menu> Commissioning > Settings > .... or
Main menu > Settings > Aggregates > Refrigeration demand >
Operating line Range Factory setting
Limit value request on 0...100% 10%
Limit value request off 0...100% 5%
Control action Slow, Medium, Fast Medium
Request evaluation Average, Maximum Maximum
This settable value prevents entire plants from being switched on (e.g. refrigeration
plant) in the case of extremely low refrigeration requests. Switching on (i.e. routing
as a bus signal or to outputs Q, d, Y, a) takes place only when the set value "Limit
value request on" is exceeded.
[%]
On
Off
3123D10en
Limit value
req off
Limit value
req on
The control action of the flow temperature on the setpoint shifts can be adapted
with the following setting in three steps (slow, medium, fast) to adapt to the plant.
Setting "Request evaluation" is used to determine if the max value or the average
of the requests is to be used:
 Setting maximum adjusts the flow temperature so that the valve position of the
consumer with the greatest demand is 90%
 When using the average setting, the flow temperature is readjusted so that the
valve positions of the 4 largest consumers are 90% on average
Note: This setting does not ensure that the refrigeration demand of all
consumers can be satisfied. However, it ensures that an individual consumer
cannot force the flow temperature to a low level (e.g. because a window is
open).
Purpose and function
Configuration
"Limit value request on"
Control action
Evaluation of request