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user instructions 711 HULMAN STREET
TERRE HAUTE, IN 47802
PO BOX 2128
812-235-6167
FAX 812-234-6975
Instruction Notes for LimiTrol
104A PC512 & 104A PC524
General Description
The LimiTrol is an analog high-limit overtemperature control with digital display of
setpoint. Operation is stable in ambient temperature from 32 to 130 degrees Fahrenheit.
Control Features
1. On/Off switch
2. 7.5 amp electromechanical relay output
3. Calibration in C.
4. Temperature range of -210 to 1038 degrees C.
5. Isolation of sensor and circuitry from line and load.
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How to Setup and Operate
First connect the heater load (7.5 amps or less) and the thermocouple plug to the load and
thermocouple receptacles on the rear of the control. Next, plug the control line cord into
the appropriate 3-wire grounded power receptacle.
Push the power switch to the βONβ position to apply power to the control. Press the
set/reset key and turn the control knob to the desired temperature setting. Release the
set/reset key once the desired temperature setting is set. The control will apply power to
the load until the temperature setting is exceeded. Once the setting is exceeded, power
will be removed from the load and a manual reset is required. The control is accurate
within +/- 1% of full scale.
Control Sensor
The LimiTrol is furnished with a TC105 thermocouple. This probe is an Iron-Constantan
thermocouple in a 6β stainless steel sheath. It is furnished with a 48β extension wire with
stainless steel overbraid and a polarized plug. The control may be used with any Type J
thermocouple which has a lead resistance less than 100 ohms.
Proper placement of the thermocouple can eliminate many problems in the total system.
The probe should be placed so that it can detect any temperature change with little
thermal lag. In a process that requires fairly constant heat output, the probe should be
close to the heater. In processes where heat demand is variable, the probe should be close
to the work area. Some experimenting with probe location can be tried to provide
optimum results.
Maintenance
Simple preventative maintenance steps include keeping the controller fairly clean. Protect
it from excessive dirt, oil and corrosion.
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