Basic Documentation

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Siemens Universal controllers RMU710B, RMU720B, RMU730B CE1P3150en
Building Technologies Frost protection (basic types A and P) 03.10.2011
"Identification" is used to select the detector / unit frost. One of the following frost
protection functions becomes active depending on the setting:
 Type of unit: Frost protection unit.
 Active DC 0… 10 V = 0… 15 ° C: 2-stage frost protection, frost protection
detector with active signal DC 0...10 V = 0...15 °C, for frost protection on the air
side
 Passive LG-Ni1000: 2-stage frost protection, frost protection detector with
passive LG-Ni 1000 signal, for frost protection on the water side
To enable 2-stage frost protection on the water side to work properly, a heating coil
pump must be installed and the outside temperature must be available (see section
8.4 "Outside temperature").
In addition, frost prot
ection must be assigned the controller to which the relevant
heating coil is connected.
The following compiles the proper configuration for the frost protection function:
Frost protection
function
Operating line Setting
Input identifier N.Xn Frost protection
Identification Monitors
Frost protection unit
Control loop with risk of frost Controller 1...3
Input identifier N.Xn Frost protection
Identification
Active DC 0...10 V = 0...15
°C (air side)
2-stage frost
protection on the air
side
Control loop with risk of frost Controller 1...3
Input identifier N.Xn Frost protection
Identification Passive Ni1000 (water side)
2-stage frost
protection on the
water side
Control loop with risk of frost Controller 1...3
If the frost protection function and the frost protection unit are acting simultaneously
(e. g. frost protection on control loop 2 acting and frost protection unit 2) on a
control loop, the maximum acts on the controllers for the two frost functions.
The current state of the heating / cooling changeover is "cooling" and frost is
detected, a frost fault is generated and the plant is shut down. The frost function
acts on all aggregates connected to sequences 1 and 3 for the control loop with
risk of frost.
The maximum of all frost functions acts directly on the pumps when one or more
pumps have the operating line frost priority set to Yes.
If, at the same time, there are other influences acting on the sequence controller,
the priority order used is that described in section 11.1.3 "Priority of functions".
Identification
Control loop with risk of
frost
Notes