Watlow EZ-ZONE RME - Manual (Page 86)

Watlow EZ-ZONE ® RME Module • 83 • Chapter 6 Features
50 percent output
3 ON, 3 OFF
66 percent output
6 ON, 3 OFF
Retransmitting a Process Value or Set Point
The retransmit feature allows a process output to
provide an analog signal that represents the set point
or process value. The signal may serve as a remote
set point for another controller or as an input for a
chart recorder documenting system performance over
time.
In choosing the type of retransmit signal the op-
erator must take into account the input impedance
of the device to be retransmitted to and the required
signal type, either voltage or milliamperes.
Typically, applications might use the retransmit
option to record one of the variables with a chart re-
corder or to generate a set point for other controls in
a multi-zone application.
Outputs 1 to 3, 7 to 9, 13 to 15 and 19 to 21 can be
ordered as process outputs. Assign an analog source
to Output Function to accomplish retransmit of a
process or set point value.
Note:
The active set point is not retransmitted, only the
user requested closed loop set point which may not be
the closed loop set point in control. Retransmitting a
profiling closed loop set point is not allowed.
Retransmit
Retransmit Source
Output Scale
Range High
Range Low
Scale High Scale Low
Compressor Control
The compressor control can save wear on a compres-
sor and prevent it from locking up from short cycling.
A bypass valve operated by a control output regu-
lates how the process is cooled, while another output
switches the compressor on and off. The compressor
will not turn on until the output power exceeds the
Compressor On % Power for a time longer than the
Compressor On Delay. The compressor will not turn
off until the output power exceeds the Compressor
Off % Power for a time longer than the Compressor
Off Delay.
0% Compressor
On Power
Off
On
100%
2%
0%
-100%
Compressor On Delay = 45 Seconds
Compressor Off Delay = 20 Seconds
2% Compressor
Off Power
Time In Seconds
% Power
Heat
Cool
Compressor
Motorized Valve Control
A motorized valve is used is to regulate the flow of
fluid which in turn impacts the loop process value. A
valve is opened or closed by closing contacts to drive
the value in the intended direction. This feature is
configured by selecting Motorized Valve as the func-
tion in the Setup Page, Special Output Function
menu. Source Function A is selected for either Heat
or Cool Power then entering the Valve Travel Time
and Deadband.
Lastly, program the outputs which will open and
close the valve. The algorithm will calculate Dead
Time which is the minimum on time that the valve
will travel once it is turned on in either the closed or
open direction. Dead Time = Valve Dead Band / 100
* Valve Travel Time.
Output 1 = Close
Temperature
Sensor
Gas Furnace
Output 2 = Open
Gas Flow
Valve
Actuator
®
Alarms
Alarms are activated when the output level, process
value or temperature leaves a defined range. A user
can configure how and when an alarm is triggered,
what action it takes and whether it turns off auto-
matically when the alarm condition is over.
Configure alarm outputs in the Setup Page before
setting alarm set points.
Alarms do not have to be assigned to an output.
Alarms can be monitored and controlled through the
front panel or by using software.