Amphenol Kaye CTR-40, Руководство пользователя, Страница: 42 / 84

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7 General Operation
When powered on the control panel display will briefly show a four digit num-
ber. This number indicates the number of times power has been applied to the
bath. Also briefly displayed is data, which indicates the controller hardware
configuration. This data is used in some circumstances for diagnostic purposes.
7.4 Heater
The temperature controller precisely controls the bath heater to maintain a con-
stant bath temperature. Power is controlled by periodically switching the heater
on for a certain amount of time using a solid-state relay.
The front panel red/green control indicator shows the state of the heater. The
control indicator glows red when the heater is on and green when the heater is
off. The indicator pulses at a constant rate when the bath is maintaining a stable
temperature.
7.5 Temperature Controller
A unique hybrid digital/analog temperature controller controls the bath temper-
ature. The controller offers the tight control stability of an analog temperature
controller as well as the flexibility and programmability of a digital controller.
The bath temperature is monitored using a platinum resistance sensor as the
control probe. The signal is electronically compared with the programmable
reference signal, amplified, and then passed to a pulse-width modulator circuit
that controls the amount of power applied to the bath heater. The bath is opera-
ble within the temperature range given in the specifications. For protection
against a solid-state relay failure or other circuit failure, the micro-controller
automatically turns off the heater with a second mechanical relay anytime the
bath temperature is more than a certain amount above the set-point temperature.
In addition to this protection, the controller is also equipped with a separate
thermocouple temperature monitoring circuit that shuts off the heater if the
temperature exceeds the cutout set-point.
The controller allows the operator to set the bath temperature with high resolu-
tion, set the cutout temperature, adjust the proportional band, monitor the
heater output power, and program the controller configuration and calibration
parameters. The controller may be operated in temperature units of degrees
Celsius or Fahrenheit. The controller is operated and programmed from the
front control panel using the four key switches and digital LED display. Re-
mote digital operation with the controller is possible via the standard RS-232
serial port. Operation of the controller using the front control panel is discussed
following in Section 8, Controller Operaton. Operation using the digital inter-
face is discussed in Section 9, Digital Communication Interface.
When the controller is set to a new set-point, the bath heats or cools to the new
temperature. Once the new temperature is reached, the bath usually takes 15–20