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Setting:
PROPORTIONAL, PROPORTIONAL AMBIENT SSR (CM 2000+), PROPORTIONAL AMBIENT
CONTACTOR (CM 2000+) or DEADBAND
Procedure: Select the desired control technique. Note that deadband control and proportional
ambient contactor should be selected when using contactors or when precise control and
advanced current handling functions are not required.
IMPORTANT: If deadband control is selected, a DEADBAND setting will be available in the
control module configuration menu, otherwise, a PROPORTIONAL BAND setting will be
available.MAXIMUMPOWER,SWITCHCURRENTRATINGandCIRCUITBREAKERCURRENT
RATING settings are not available when the control module is set to operate in either contactor
mode. If proportional ambient contactor is selected, the CYCLE TIME setting will also be
available.
3.4.5 DEADBAND SETTING
(Deadband control mode only).
Purpose: If a control module is not configured as an ATC SLAVE and is equipped with a
contactor, to control a heating circuit, it is necessary to use deadband rather than proportional
control. This is done to prevent the contactor from switching on and off rapidly and wearing
out prematurely. This deadband uses on/off control, where the decision to turn the output off
or on is based upon the difference between the measured control temperature and the desired
CONTROL SETPOINT temperature.
Range: 5 to 90°F (3 to 50°C) for CM 2000
2 to 90°F (1 to 50°C) for CM 2000+
Procedure: Adjust the DEADBAND setting to achieve the desired level of temperature control.
When the control temperature is above the setpoint + deadband value, the control module will
turn off its output. If the control temperature drops below the setpoint, the output will be turned
on. Note that the smaller the DEADBAND setting, the more often the contactor will cycle on
and off, decreasing its operational life.
IMPORTANT:
• See Section 5.2 of this manual for an explanation of Deadband Control. Note that the
MAXIMUMPOWER,SWITCHCURRENTRATING,andCIRCUITBREAKERCURRENTRATING
settings are not available when the control module is set to deadband control mode
(typically when switching a contactor).
• The DEADBAND must be set when a control module is configured as an ATC MASTER and
its SWITCH CONTROL MODE is set to PROPORTIONAL. This is because the ATC output
signal from the Master control module will use the deadband control mode to control any
Slave control modules.
3.4.6 PROPORTIONAL BAND SETTING (CM 2000+ ONLY)
(For use with the three proportional control modes only).
Purpose: If a control module is not configured as an ATC SLAVE and uses an SSR to control the
heating circuit, then proportional or proportional ambient SSR modes are normally used, allowing
for more precise temperature control. When using contactors, and control decisions are to be
made based on the ambient temperature, the proportional ambient contactor mode is used.
This programmable proportional band acts to vary the on to off time of the output based
on the difference between the measured control temperature and the desired CONTROL
SETPOINT temperature.
Range: 2 to 90°F (1 to 50°C)
2 to 630°F (1 to 350°C) for versions V3.19+ only
Procedure: Adjust the PROPORTIONAL BAND setting to achieve the desired
temperature control.
IMPORTANT:
• See Section 5.2 of this manual for an explanation of how the three proportional modes use
the PROPORTIONAL BAND setting.
• For the CM 2000 control modules (V2.35 and lower), the PROPORTIONAL BAND is fixed at
2°F (1°C), and centered around the CONTROL SETPOINT temperature.
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