6
General Operation
6.1
Control System
The 2200 temperature controller is not specified for use with a particular sys-
tem. Its flexibility enable it to be used with a large variety of control systems.
Often the controller is used with a precision constant temperature bath.
It is the responsibility of the user to ensure that the components are chosen and
the system constructed to ensure safe and proper operation of the complete sys-
tem. The user should have a good knowledge of and experience with, electrical
fundamentals and wiring practices as well as control systems. Hart Scientific
cannot be responsible for any damages or injury resulting from improper de-
sign or operation of the control system. For more help or information, contact
an Authorized Service Center.
6.2
Temperature Controller
The system temperature is controlled by Hart Scientific’s unique hybrid digi-
tal/analog temperature controller. The controller offers the tight control stability
of an analog temperature controller as well as the flexibility and programmabil-
ity of a digital controller.
The temperature is monitored with 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 which
controls the amount of power applied to the heater.
WARNING:
For protection against solid-state relay failure or other cir-
cuit failure, a bi-metallic cut-out should be used.
The controller allows the operator to set the set-point temperature with high
resolution, 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. The controller is equipped with an
RS-232 serial digital interface for remote operation. Operation of the controller
using the front control panel is discussed following in Section 7. Operation us-
ing the digital interface is discussed in Section 8.
When the controller is set to a new set-point the system will heat or cool to the
new temperature. There may be a small overshoot or undershoot of about 0.5°C
or more depending on the system and proportional band.
21
6 General Operation
Control System
