Pacific Sensor Technologies has introduced PST-UPS-500 resistive type humidity sensor for non-condensing environment excitation voltage 1 VAC @ 33 Hz to 10 KHz. Range of operation of the PST-UPS-500 resistive type humidity sensor is 20% to 90 % @70 °F +/- 2%, temp. -20 to +160°F.
The PST-UPS-500 resistive type humidity sensor has a reverse logarithmic output. The PST-UPS-500 resistive type humidity sensor is available as signal conditioner and sensor SC-500
The PST-UPS-500 resistive type humidity sensor consists of a ceramic substrate having interleaved noble metal electrodes coated with a hygroscopic polymer. When excited by a low level symmetrical AC signal, the PST-UPS-500 resistive type humidity sensor’s impedance varies in an inverse logarithmic function proportional to the relative humidity.
A low AC signal, typically less than 1 VAC, is used to prevent polarization or self-heating of the iPST-UPS-500 resistive type humidity sensor.
To measure the PST-UPS-500 resistive type humidity sensor's impedance, a sine or square wave of 1 to 3 V rms in the frequency range of 60 Hz to 10 KHz is used. To avoid long-term polarization, the wave shape should be symmetrical, that is, no DC offset. The commonly used excitation frequency is 1 KHz 10 KHz).
The capacitance of PST-UPS-500 resistive type humidity sensor
The PST-UPS-500 resistive type humidity sensor’s impedance includes a capacitive component. This capacitance vs. RH @ 25º C the logarithmic capacitance varies from 10 to 10,000 Pico Farads and covers several decades.
The PST-UPS-500 resistive type humidity sensor response time is expressed in terms of absorption (the taking in of moisture by the sensor) and desorption (the freeing of moisture from the sensor).
The applications of the PST-UPS-500 resistive type humidity sensor include:
HVAC controls, humidistat, appliances, compressed air, medical instruments data loggers, ideal for OEM applications, industrial controls, control chambers building automation, humidification and dehumidification.
The PST-UPS-500 resistive type humidity sensor has the following specifications. They are:
- Range 20-90%RH at 77ºF
- Accuracy ±2% RH
- Interchangeability within 2% RH
- Hysteresis +/- 1% RH
- Long term drift <2%RH/5 Years
- Response 5 seconds/63% step change
- Temp. coefficient -0.4%RH/°F (Average at 20-80% RH from 60-100ºF)
- Temperature limits -4 to +140°F
- Excitation voltage 1 VAC., symmetrical
- Excitation frequency 33-10 KHz
- NIST traceable certification is available