Libratherm offers Microcontroller based Humidity and Temperature Controller Model DTH-966-C with input and output suitable for measuring and controlling the T and RH of stability or environmental test chambers or walk-in chamber. These chambers are mainly used in Pharma, Petroleum, Chemical, and Food Industries to test and store the product/sample under the desired simulated and control climatic environment.

The Fogger/Heater and Actuator Controller DTH-966-C accepts input from the standard T + RH sensors consisting of (Pt-100) temperature sensor and the capacitive type RH sensor or from direct T + RH sensor/transmitter. (The suitable sensors or transmitters of international brands can be used along with this controller). The input signal is processed by 12 bit ADC for a very accurate and stable display. The time tested PID algorithm gives accurate control of Temperature and %Rh. The single controller has the advantage of tracking and synchronizing the two different process parameters over individual control for temperature and %RH.

In model DTH-966-C, the process values and set values are alternatively displayed on 2 independent 4 digits 7-segment Red / Green LED displays.

Since these controllers are basically designed for the stability chambers, the accurate control of temperature and humidity is achieved by operating the air heater (for Dry heat) and the boiler heater (for Moisture or water vapor) in the PID control action, and the compressor (for low temperature – below ambient) is operated in On-Off action with user-programmable time delay facility. Since the compressors are not required to be kept ON above a certain level of temperature, the user-selectable mode is provided to program the compressor operation in AUTO, Continuous ON or permanent OFF mode. To de-humidify the system, an extra ON/OFF output is provided to operate either the same compressor or an extra compressor – with a time delay function. All the control outputs are in the form of SSR drivers of (10 to 12) VDC pulse to control the Air heater, Boiler Heater and Compressor, and Dehumidifier through external Solid State Relays.

In case of water level low, the audible alarm is generated and heaters are turned off to prevent dry run and safety.

DTH-966-C has many other useful features:
1. DTH-966-C accepts 2 nos. of external potential-free contacts (DI) to detect the water level of the boiler used for generating the steam or water vapor and to monitor the Open/Close status of the front door of the chamber – through limit switch contacts.
2. DTH-966-C optionally offers serial communication port RS-485 over MODBUS RTU protocol for interfacing to the computer for data logging and storage purpose.

Key Features:

• Microcontroller based design.
• Easy front panel keyboard programmable.
• Independent 4 control outputs for Temperature/%RH control (4 x DO).
• Digital input for water level, door switch, etc (2 x DI).
• User programmable alarm limits with auto snooze facility.
• PID or ON/OFF control action for Air heater, Boiler heater and ON/OFF control action for Compressor with programmable time delay.
• RS-485 port for computer interface.