TC-10 User Manual
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version 3.9
page 10
3.3. Rear Panel Elements
LINE VOLTAGE SELECTION: The selector for the line voltage and the connector for the
power cord are located in a mains connection module on the rear panel of the instrument.
Caution
:
If operated with other line voltage the instrument may be damaged if the wrong line
fuse is installed!
FUSE: The fuse is also integrated in the mains connection module. The line fuse must be 3.15 A
slow (115 V) or 1.6 A slow (230 V). It must be replaced only by specified type (see above).
Please disconnect mains power plug before replacing fuse.
3.4. Electronic Control and Protection Circuits
CONTROL LOOP
The sensor / thermometer, PI-controller, output power stage and heating element form a closed
loop control system. The desired temperature signal is compared with the output signal obtained
from the thermometer giving an error signal. This signal is amplified in the PI controller and
transferred to the output stage where it is converted to a high-power output signal applied to the
heating element.
ELECTRONIC PROTECTION CIRCUITS
Each system is equipped with two protection systems:
1.
Sensor inputs: an electronic shut-off function disconnects the output if the sensor is
disconnected, broken or short-circuited.
2.
Output protection: the output current and voltage are limited electronically.
Important
:
The sensor used for the control must be in good thermal connection with the heating
wire, if not, overheating and damage may occur.
ALARM circuit
The internal thermometer (R2252 sensor) inputs are protected by the sensor alarm circuit (see
above). If this thermometer is used as input device for the PI controller, the ALARM circuit
disconnects the power output if the sensor is damaged or not connected. This state is indicated
by the red ALARM LED. If the DIRECT mode or EXT mode is used the ALARM circuit is
disabled.
ACCURACY
Measuring accuracy of the internal thermometer is 0.1°C, controller accuracy is 0.5°C or better
(depending on the amount of heated solution).