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T775J ELECTRONIC REMOTE TEMPERATURE CONTROLLER
63-2248—4
14
temperature goes down, the control point goes down). The
type of ratio is selected by using the two DIP switches
provided.
The four possible reset operating configurations are illustrated
and explained in Fig. 18. Switches 1 and 2 are shown but
switches 3 and 4 are unused; however, the location of these
DIP switches is shown in Fig. 5.
CAUTION
A reset ratio lower than one can result in unstable
control. Widening the throttling range and/or
differential minimizes this effect.
Proportional + Integral Modulating Control
Proportional + Integral (P+I) control provides fast, responsive
operation of the controlled devices in reacting to temperature
changes by providing an output signal proportional to the
deviation between setpoint and actual temperature. An
integral proportion also provides a time dependent output
signal that is dependent on the length of time of the deviation
between actual set point and sensed temperature.
The P + I algorithm places the control setpoint in the middle
of the throttling range. A deadband around setpoint exists and
is proportional to the throttling range. For the T775, this
deadband is 1/8 of the throttling range.
There are three modulation options available for the T775J
(see Fig. 20 for modulating output connecting terminals).
Fig. 18. Reset switch configuration.
Fig. 19. Summary of action/direction switches.
PWB
SWITCH
SWITCH
PWB
OPEN
CLOSED
SIDEVIEW
OPEN
CLOSED
RESET DIRECTION SWITCH
RESET ACTION SWITCH
RESET DIRECTION SWITCH: WILL RESET
THE COUNTROL POINT UP (WHEN
OPEN) OR DOWN (WHEN CLOSED).
RESET ACTION SWITCH: RESET IF THE
OUTDOOR TEMPERATURE (SENSOR B) IS
ABOVE (WHEN CLOSED) OR BELOW
(WHEN OPEN) THE OUTDOOR
TEMPERATURE SETPOINT.
1
2
OPEN
CLOSED
OPEN
CLOSED
OPEN
CLOSED
OPEN
CLOSED
RESET DIRECTION SWITCH CLOSED
RESET ACTION SWITCH CLOSED
IF THE OUTSIDE SENSOR (B)
TEMPERATURE IS ABOVE THE OUTSIDE
TEMPERATURE SETPOINT,THE CONTROL
POINT WILL BE DECREASED BY THE
RESET RATIO.
1
2
RESET DIRECTION SWITCH OPEN
RESET ACTION SWITCH CLOSED
IF THE OUTSIDE SENSOR (B)
TEMPERATURE IS ABOVE THE OUTSIDE
TEMPERATURE SETPOINT,THE CONTROL
POINT WILL BE INCREASED BY THE
RESET RATIO.
1
2
RESET DIRECTION SWITCH CLOSED
RESET ACTION SWITCH OPEN
IF THE OUTSIDE SENSOR (B)
TEMPERATURE IS BELOW THE OUTSIDE
TEMPERATURE SETPOINT,THE CONTROL
POINT WILL BE DECREASED BY THE
RESET RATIO.
1
2
RESET DIRECTION SWITCH OPEN
RESET ACTION SWITCH OPEN
IF THE OUTSIDE SENSOR (B)
TEMPERATURE IS BELOW THE OUTSIDE
TEMPERATURE SETPOINT,THE CONTROL
POINT WILL BE INCREASED BY THE
RESET RATIO.
1
2
M8110A