OUTPUTS
The Series 800/850 TEC Controllers are equipped with Output 3 which is an
internally wired option giving the user a configurable high and/or low Temperature
Limit Alarm. Output 3 also adds a “Soft Start” to the controller which eliminates any
potentially harmful spikes of current during power up. Normally this is not a problem
due to the power requirements of the thermoelectric devices and their current
handling capabilities. However, in certain circumstances it is desirable to eliminate
this altogether (i.e. very small TEC with high power controller).
Output 4 is optional and can be ordered as either an Analog Retransmit Output or a
digital communications channel capable of EIA/RS-232 or EIA/RS-485.
Output 3 Detail
Optional output 3 is essentially software AND hardware. The software part includes
the Temperature Limit Alarm options which will signal the user if the controller
should go outside of user specified temperatures. The hardware part is what
actually turns the output off in case of an alarm.
The Temperature Limit Alarm allows the Series 800/850 TEC Controllers to “alarm”
the user of preset high or low Temperature Limits that are controlled via the front
panel of the Series 800 Thermoelectric Cooler Controller.
When either of the Temperature Limit Set points ([a3lo] and [a3hi]) are
exceeded the Series 800/850 TEC Controller will turn off the TEC power output.
The hardware part of Output 3 is a single pole double throw relay. This relay is
internally wired to accomplish both a Soft Start condition and allow for setting
Temperature Limit Alarms that automatically shutdown the output when an alarm
condition is met. This is called Automatic Temperature Limit Shutdown
A Soft Start of the Series 800/850 TEC Controllers is accomplished by keeping the
analog circuitry OFF while booting up. This is done by setting up the Output 3 Alarm
so that the NC (normally closed) contacts of the Output 3 relay short out the
CTRL-IN input pins 1 and 6 (internally). This will keep the output of the Series
800/850 TEC Controllers OFF until the Alarm is sensed as being OFF or “o.k.”. At
this time the relay will turn ON (opening the NC contacts) and allow normal
operation. At any time there is an alarm condition the output will be “shutdown”.
Please note that this is a “Fail Safe” condition. The relay will turn off if there is a
power loss condition and immediately shut down the output. Therefore it is
imperative that the Output 3 logic be set to “O” for OPEN. This will OPEN the
normally closed contacts when not in an alarm condition.
ALPHA OMEGA INSTRUMENTS CORP. Instruction Manual
Series 800/850 Thermoelectric Cooler Controller Page 97
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