TC 120
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enter the system well ahead of the pump, allowing it to blend with the system water. The
water supply temperature governs the minimum operating temperature of the unit.
For closed circuit operation, the unit cools by automatically releasing cooling water through
the tubes of the specially designed shell and tube heat exchanger in each zone. The process
fluid, such as water, glycol, or other similar fluid, is circulated through the shell of the heat
exchanger.
The plant water supply temperature governs the minimum operating
temperature of the unit.
Electricals
The pump motor and the immersion heater operate on three-phase 50/60 cycle
nominal voltages with the control circuit operating at 115V single phase. The control
circuit voltage is provided by a single phase machine tool transformer with a
grounded secondary.
The 115V control circuit is fuse protected. The pump motor is controlled by a full
voltage magnetic non-reversing motor starter, with overcurrent and thermal overload
protection.
Automatic Vent
This feature automatically triggers a quick and complete purge of air from the system
before you start the unit. The vent actuates the solenoid valve, and forces trapped air
and water out through the drain, properly filling and priming the unit prior to startup.
Complete venting is necessary to prevent damage to the pump and heater.
Pressure Switch
A pressure switch built into each unit keeps the system from starting until the water
supply is turned
On
and subjected to the minimum water supply pressure. This
feature protects the pump seal and the heater from damage through attempted
operation without water. The switch also shuts down the unit if the
COOLING
WATER IN
or
MAKEUP
water pressure drops below the threshold. The pressure
switch is set at approximately 16 psig (110 kPa/1.1 bar) for 250°F (121ºC) units or 55
psig (379 kPa/3.8 bar) for 300°F (149ºC) units prior to leaving the factory.
4-2 The Microprocessor Controller
NOTE: For more information or for the M2C controller option, please see the included
separate controller manual.
The controller is an easy-to-operate microprocessor-based PID control device. When the
process reaches the set point, the PID control cycles the cooling valve and/or immersion
heater to maintain the proper leaving water temperature.