Space Air Temperature Sensors, RTD Transmitters

Space Air Temperature Sensors

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Can fit temp & rH in one box
Convenient 2 part construction
Housing matches installations

Space Air Temperature Sensors
New High Ventilation Design has ventilation slots 50% larger than some competitors allowing more air to flow past the sensor providing faster response and more accurate readings.

Our new two piece construction is more convenient to install than the the older three piece construction still used by some suppliers. Our ABS plastic molding is fire retardant.

We mount the sensing element and a "Phoenix" terminal strip securely on a circuit board.

NTC Thermistors are the most sensitive sensors from -50°C to +150°C with temperature coefficients as high as several percent per degree C. This means that lead resistance has minimal effect on system accuracy. Our standard thermistor has a 10K resistance at 25°C and a tolerance of ± 0.2°C. Other calibrations and accuracies are available.

Platinum RTD's are the most stable temperature sensors between -50 and 400°C. They show almost no calibration drift with time. Their stability, wide temperature range and almost linear output make them the choice in demanding applications. Our standard RTD uses a 100 ohm thin film element to DIN 43 760 (IEC 751) with a tolerance of 0.3°C. We also supply 1000 ohm and wire wound elements.

4-20mA Transmitters using 100 ohm RTD's are available in the same housing when RTD's have been specified for use with a panel that will not accept RTD's directly. For this choice change the TS designation in the order number to TT and specify the range.

Time override is available with our optional tactile feedback push button which is mounted under the decorator plate. A simple closure can alert the DDC to begin time override operation for the particular zone. More complex customer specified circuitry can be supplied on request. Specify option TOS.

Local Setpoint override is available with our integrated slide potentiometer. This provides a variable 1 to 11K resistance signal at built-in terminals. A DDC panel could change the setpoint by ±3 degrees dependent on the resistance value. Specify option SS.

Space Air Temperature Sensors - Installation & Operation

Temperature Sensors

Installation

This unit is provided with two holes suitable for switch box or dry wall mounting. A two pole terminal is provided for hook-up and a hole through the circuit board and the back of the case is provided for wiring. All Enercorp thermistor temperature sensors are unaffected by polarity or position. Units with time over-ride (TOS) or setpoint over-ride (SS) features have labelled terminal blocks. All other versions are supplied with 22 awg leads.

Troubleshooting

Problem	Cause
Sensor reads 0 or only a few ohms	Sensor or leads are shorted
Sensor reads over full scale or very high	Sensor or leads are open
Readings are erratic	Loose connection

Calibration
These sensors have no built-in means of calibration. Minor adjustments must be made at the receiving instrument or DDC panel. If an adjustment of more than a degree is required first check your connections. If the connections are good the sensor may have been damaged by operation outside it's temperature range or mechanical causes. Damaged sensors can not be repaired and must be replaced.

RTD Temperature Transmitters

Installation

This unit is provided with two holes suitable for switch box or dry wall mounting. A two pole terminal is provided for hook-up and a hole through the circuit board and the back of the case is provided for wiring. All Enercorp RTD temperature transmitters are unaffected by position, and are reverse polarity protected.

Troubleshooting

Problem	Cause
No reading	1. Lead wires are reversed 2. No power to board - check voltage is between 13 and 30 VDC
Reading too low or too high	1. RTD wires shorted or RTD defective. Check that RTD resistance is about 100 ohms + 0.4 ohms/degree C above 0°C. 2. Check for correct transmitter range. 3. Check for condensation or mechanical damage to board.
Readings are erratic	Loose connection. Screw down all connections tightly.

Calibration

These transmitters have clearly marked zero and span pots. To calibrate connect a precision decade box to the RTD terminals. Since 1 degree Fahrenheit change is equal to a 0.2 ohm change you need a very accurate decade box to calibrate accurately. Insert a DVM set to mA in the 2-wire loop and apply power. With the decade box set to the scale beginning resistance from the table adjust the zero pot to obtain 4 mA. Change the resistance in the decade box to the scale end and adjust the span pot as necessary to obtain 20 mA. Go back and forth until the readings are stable.