Parr Instrument 4875 - Manual (Page 8)

4875 Power Controller
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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