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Building Technologies Division  User Manual RWF55...  CC1U7867en 
Infrastructure & Cities Sector  5 Operating modes  05.11.2013 
5.2.4  2-stage burner, analog output  
 
In this case, a digital standard signal switches the second stage on via the analog 
output (terminals A+ and A-) when reaching switch-on threshold HYS1 and off at the 
lower switch-off threshold HYS2. 
 
A
7866d08/0911
 
Figure 11: Control sequence of 2-stage burner, analog output 
 
If the controller is set to cooling mode, the respective values of HYS4, HYS5 and HYS6 
apply. 
 
Starting from a high actual value, the controller now controls the connected cooling 
equipment in low-fire operation. In high-fire operation, the second stage and thus the 
cooling output are controlled via relays K2 and K3 or the analog output. The response 
threshold (q) calculates automatically (now in the reverse sense) the point from which 
the cooling output is to be increased. 
 
Cooling controller