User Manual

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Siemens Switching and monitoring device RMS705B CE1P3124en
Building Technologies Aggregates 01.04.2010
8.3 Rotary step switch
Use this function to control multi-stage aggregates depending on load or control
several aggregates and be used as lead/lag control.
You can configure the rotary step switch using a selectable step switch type (3
types available for selection).
T he rotary step switch can be configured as:
 Linear step switch
- Switch equal stages or aggregates with equal output (max.4 per function
block).
- Lead/lag control (run priority changeover) with selectable changeover types for
the same number of operating hours.
 Flexible step switch
Optimum switching of aggregates with different outputs to ensure that as few
aggregates as possible are operating and to achieve optimum control under
partial load conditions (max. 4 stages).
 Binary step switch
Switching binary stepped aggregates. Max 15 stages can be switched per step
switch. 2 step switches combined can switch max. 127 stages.
Only the linear step switch allows for lead/lag control (run priority changeover).
Inputs
CD
C D
Rotary
step switch 1
Outputs
Input Section Output Section
Precommand 8.3.8 Precommand 8.3.7
2
t
1
St
ar
Start conditions 1,2,3,4, and
co i
8.3.11
nt nuous
Command 8.3.5
Fault status message aggregates
8.3.12
A,B,C,D
Load 8.3.6
Explanation of symbols
Purpose
Note