Temperature and Humidity Controller for HVAC – DTH-948

Temperature and Humidity Controller for HVAC – DTH-948

Product Description :

DTH-948 – Micro controller based PID/On-Off Temperature & Humidity controller. Two input and two PID/On-OFF control outputs with alarms.
Size (H x W x D) – 96 x 48 x 120 mm

Libratherm offers PID/On-Off Temperature and Humidity Controller AHU-948 for controlling temperature (T) and relative humidity (Rh) for the Air Handling Unit and other similar HVAC applications. For the proper functioning of the Air Handling unit, it is required to monitor the T and RH of the Air being delivered to the Production or Service Area. The T and RH values are to be compared with the desired set values and based on the error between the process values and set values the operation of the hot/cold water 2 way or 3-way valves/damper Actuators, Heaters, Cooling coils are controlled to maintain the T and Rh in the Airflow processed by the AHU systems.

This Digital Temperature and Humidity Controller AHU-948 accepts inputs from a standard T + RH sensor or transmitter. The instrument simultaneously displays the temperature and relative humidity. The PID outputs are available for controlling temperature and %RH in the form of 4-20mA/(0-10)VDC and /or in the form of DC/logic pulses. Common or individual High and Low alarm output in the form of relay contacts for Temperature and humidity can be provided as per the user’s requirement. To meet specific AHU Temperature control applications, the 3-way valve can be operated by 4-20mA/(0-10VDC proportional PID in direct action. To control RH, the DC pulse or 4-20mA/0-10VDC output is available, which can be used to control AC or DC operated solenoid valves or to control the heating using Libratherm make – single or three-phase thyristor control. RS485 serial port is available for interfacing DTH-948 to DDC or PLC or BMS.

Key Features :

Microcontroller based design.
Elegant appearance, easy to operate and compact in size.
Highly accurate and sturdy in operation.
User programmable settings.
Dual display for simultaneous indication of T and RH.
Field proven Algorithm, tested successfully for various AHU / HVAC control applications.

Parameters	Description
Input from T+RH Transmitter	4-20 mA from T + Rh transmitter (both the inputs can be derived from Libratherm make)
Input from T+RH Direct Sensor	(0-1)V, (0-3.3)V and/or direct Pt-100 sensor. (Like Hygroclip-XD or HTS-220/HTS-440)
Range	0.0 °C to 60.0 °C for temp. (Optional upto 80.0 °C) & 0.0 to 100.0 % for RH. (Programmable Span Hi and Span Lo)
Resolution	0.1 °C for Temp. and 0.1 % for RH
Indicating Accuracy	+/- 0.3oC for Temp. and + / - 0.5% for RH. (Subject to accuracy of the sensor/transmitter used in the system)
Display	4-digit 0.3" Red 7-segment display for Temp. in °C. 4-digit 0.3" green 7-segment display for RH in %. Front Panel LED indications for Control outputs and alarms.
Control Action	PID - User selectable Direct and Reverse action.
(Direct/Reverse)	(In DIRECT action the control output increases as the process value approaches towards the set value and In REVERSE action the control output decreases as the process value approaches towards the set value)
Control Output	a) Dual 4-20 mA or 0-10VDC/0-5VDC for T and RH control b) Dual DC pulse (0 to 12)VDC - for T and RH (PID + On-Off)
Control settings	Set points PID and On-Off hysteresis values for T and Rh are individually programmable through key board.
Alarm settings	High and Low settable for each T and RH with programmable Hysteresis.
Alarm Outputs	2 sets of relay contacts - (C1-NO1), (C2-NO2)
Tuning	Manual tuning of PID values.
Memory Backup	Retention of PID and Set values in the built in non-volatile memory in case of power failure and automatic re-execution of control on power resumption.
Serial Interface (Optional feature)	Two wire RS485 on Modbus RTU Protocol for PC/DCS/PLC/BMS interface (in slave mode with user programmable ID).
Supply	90-240VAC, 50/60Hz.
Size	96W x 48H x 120D mm.
Panel Cutout	92W x 44H mm. +/- 0.5 mm.
Enclosure	ABS plastic with polycarbonate front graphic.

Sr. No.	Model	Specifications	Part No.
1.1	DTH-948	Input : 2 X 4-20mA, Output : 2 x SSR + 2 x Analog Output + 2 x Relay	3311-1
1.2	DTH-948	Input : 2 X 4-20mA, Output : 2 x SSR + 2 x Analog Output + 2 x Relay + RS-485	3311-2
1.3	DTH-948	Input : 0 to 3.3V + Pt-100, Output : 2 x SSR + 2 x Analog Output + 2 x Relay	3312-1
1.4	DTH-948	Input : 0 to 3.3V + Pt-100, Output : 2 x SSR + 2 x Analog Output + 2 x Relay + RS-485	3312-2

Product Category

Digital Indicators

Temperature Controllers

Data Loggers & Scanners

Temperature & Humidity Instruments

Thyristor Triggering Cards

Thyristor Power Controllers

Phase Angle Controllers

Zero Cross Over Switches

DC Rectifiers

Signal Isolators & Conditioners

Signal Isolator DC to DC Signal

Signal Isolator AC to DC Signal

Signal Isolator Temperature to DC Signal

Transmitters

Motor Controllers