Data Sheet for Product

Technical Instructions Polygyr-Compact Exhaust Air Temperature Controller
Document Number CM1N3405E-P25
Rev. 1, February, 2000
Page 2
Siemens Building Technologies, Inc.
Function
The RCM61.21 provides P control. The P band can be adjusted. The controller
compares the actual value with the set point and generates a proportional control signal
when a deviation occurs. The control signal is continuous and has a range of
0 - 10 Vdc. When the control signal changes from 0 – 10 Vdc, the correcting variable
changes from 0 - 100%, i.e., there is a proportional relationship between the correcting
variable and the control signal. The adjusted Xp (proportional band refers to heating
(Y1). The P band for cooling (Y2)is half as wide, making it possible to obtain the same
control quality for both heating and cooling, although the control conditions are different
(nearly the same plant gain with different correcting spans).
Between the two outputs there is a fixed dead zone. The proportional offset is zero
when the load is zero (actual value = set point).
Each control output generates a control signal of 0 – 10 Vdc. The outputs are switch in
sequence and their mode of operation is opposed: One output for heating and one for
cooling.
Y
X - W
Xp Xdz
0
10V
SASC0009R1
W
X
Xdz
Xp
Y
Set point
Actual value
Dead Zone
P band
Signal voltage
Heating
Cooling
Figure 1.
Compensation
The reference value is fed to the controller, which shifts the set point. There are two
possibilities:
•
Universal compensation over the whole setting range or over any part of the setting
range with the help of the RZF61.100 universal shift controller, or from a building
automation system.
•
Set point adjustment within ± 10% of the setting range; this is generally made from
a building automation system.
For more information on compensation, see
Application Notes
.
Low Limiting of
Discharge Air
Temperature
The RCM61.12 discharge air temperature controller serves as a limiter. Its control signal
is fed to the exhaust air temperature controller, preventing the discharge air temperature
from falling below the selected low limit value. See Technical Instructions
CM1N3406E-P25.
Design Features
The RCM61.21 is a small, electronic controller that combines controller, setting unit and
sensing element into one unit.
The casing is plastic with a removable cover, fully active flexible sensing element, and
removable mounting flange with adjustable positions.
All setting devices and connecting terminals are contained in the housing and
accessible only when the cover is removed.