RH CGS-240, Руководство пользователя

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Subsystems
CGS-240 Manual 6/15/2021
Page 69 of 148
T
CL
Figure 6.31
H3
TH3
Figure 6.30
T
EV
H4
Figure 6.32
6.5.3 CHAMBER FLUID HEATER, H3
The chamber temperature is maintained by heating or
cooling the circulating fluid as needed. Heating is
accomplished by activating a 700-watt stainless steel
insulated immersion heater, H4, inserted in the circulating
fluid. The circulating fluid temperature is warmed to and
maintained at setpoint through pulse width modulation of
the fluid heater using feedback from the chamber fluid
temperature sensor, T
CL
.
When heating is required, the ECB’s AC CONTROL – A3
digital output activates solid state relay SSR4 which
completes the AC current path through circuit breaker,
CB5, to the fluid heater.
A3’s digital output is visually indicated by an adjacent LED.
The heater ON status is also indicated with an LED on the SSR4.
AC power to the heater is also protected by a thermal cutout switch, TH3, which removes AC power in the event of
over temperature. Chamber fluid temperature influences chamber temperature. Chamber temperature is
measured by temperature probe, Tc, mounted inside the chamber.
6.5.4 EXPANSION VALVE HEATER, H4
As the gas expands from a high pressure to a lower
pressure, it cools. To offset this cooling effect, and also to
prevent unwanted condensation in the expansion valve, V2,
the valve is heated.
Heater H4 is comprised of a small heater installed in the
valve plug, and a custom heater foil adhered to the outside
of the valve body. They are connected in parallel.
Expansion valve heating is accomplished by activating the
ECB’s DC CONTROL – RLY 12 to source 24 VDC to the
heaters.
RLY 12 ’s output is visually indicated with an adjacent LED. When the LED is ON, the heaters are active.
The expansion valve is heated and maintained at temperature through pulse width modulation of RLY 12 using
feedback from the expansion valve temperature sensor, T
EV
. The valve is normally wrapped in a custom molded
thermal insulator (not shown in Figure 6.32).