Instruction Manual
4875 Power Controller
www.parrinst.com
9
sw I t c h e s  a n d  In d I c a t o r s
The motor controls consist of an on-off switch, a speed 
control knob and, local remote switch. The speed con-
trol knob should be turned down to a minimum setting 
before turning on the motor switch to minimize electri-
cal surges within the speed control unit. 
The motor on-off switch switches on and off power to 
the motor output.
The local remote switch, switches between local con-
trol using the speed control knob and remote control 
using a PC.
We do not include the speed control knob, local remote 
switch or motor switch when the reactor is equipped 
with an air motor for stirring or when the controller is 
created for use with a non-stirred vessel. 
The heat indicator shows that power is being sent to the 
heater. During a process, this indicator may light inter-
mittently as the temperature approaches the set point on 
the controller. This a normal occurrence of using time 
proportioned heating with a PID controller.
The cool indicator shows that power is being sent to the 
solenoid valve module. During a process, this indicator 
may light intermittently as the temperature approaches 
the set point on the controller. This is a normal occur-
rence of using time proportioned heating with a PID 
controller.
The high limit indicator light will indicate if the 
controller receives a signal that a high temperature or 
pressure limit has been reached and the high limit reset 
relay has opened. When the light comes on, the user 
must find the source of the problem, correct it, and then 
manually reset the system using the high limit reset but-
ton on the front of the controller. 
A high-limit reset is provided to shut-off power to 
the heater whenever any of the alarm conditions are 
reached. It can be actuated either by the high tempera-
ture alarm settings in the basic control module, or by 
the high pressure limit settings in any of the optional 
modules installed in the controller. When tripped, this 
breaker must be reset manually using the push button 
on the front panel. Often the high limit reset will trip 
when the process controller power has been cycled. 
4875 Power Controller Front Panel










