Precision Control Systems 915 - Manual (Page 12)

Page 9 of 21
Operating Instructions
Controls and Indicators
Figure 4-1 shows the location of the controls and indicators.
Main Disconnect Switch
The main disconnect switch turns on and off the power control system. Note the following:
Before turning on the disconnect switch, check the following:
• The load is wired and ready for power to be applied to it.
• All safety precautions are observed.
Heater ON/OFF Switch
The heater ON/OFF switch allows the operator to enable or disable the power going to the
load. This is accomplished by removing power from the AC contactor. This in turn removes
power from the SCR controller. The cooling on indicator must be on before the heater power
can be turned on.
Cooling ON/OFF Switch
The cooling ON/OFF switch allows the operator to turn on or off the heater cooling.
Heater On Indicator
• Indicator light on steady indicates power is applied to the heater power controller.
• Indicator light flashing indicates that the Remote Interlock is open and heater power can
not be applied.
Cooling On Indicator
• Indicator light on steady indicates adequate cooling flow.
• Indicator light flashing indicates that the cooling is in a one minute shutoff delay cycle.
The one minute delay cycle is activated any time that the heater power contactor is
opened, after the initial heater on cycle is activated.
Heater Over Temperature Indicator
• Indicator light on steady indicates a heater over temperature condition. A heater over
temperature condition will open the heater power contactor, removing power from the
heater.
• Indicator light flashing indicates a process over temperature alarm. This feature is
available only if the Temperature Control Option is installed. The indicator will flash only
as long as the process alarm exists.
Section 4