Airend discharge temperature sensor (PT100 / PT1000)

RTD in the airend discharge that feeds the high-temperature trip, typically 220 – 228 °F (104 – 109 °C).

Also called: ADT sensor · RTD · PT100

How it works

A platinum resistance element with a defined resistance/temperature curve. The controller converts resistance to temperature and trips the machine before the oil and separator element are damaged.

Specifications

PT100 at 0 °C

100.0 Ω

PT100 at 25 °C / 77 °F

109.7 Ω

PT100 at 100 °C / 212 °F

138.5 Ω

PT1000

Ten times the PT100 value (1000 Ω at 0 °C)

Typical trip

104 – 109 °C (220 – 228 °F)

Parts you can order

• Generic industrial

  Pt100 RTD probe, 3-wire

  Pt100, 1/4 in. or 1/2 in. NPT thread

  $45 – $220
• Generic industrial

  KTY83/KTY84 silicon temperature sensor

  KTY84-130 class

  $25 – $120
• IFM Electronic

  TN series temperature sensor

  TN2531

  $220 – $480
• Generic industrial

  Pt100 RTD probe, 1/4 in. NPT

  By probe length and lead configuration

  $45 – $190
• Generic industrial

  KTY84-130 / PTC motor thermistor

  KTY84-130

  $20 – $90

Field test procedure

1. Disconnect one lead and ohm the element. Compare with the table for the actual measured metal temperature.
2. PT100 reading in the 1 kΩ region means you have a PT1000 wired to a PT100 input (or vice versa) — the controller will show wildly wrong temperature.
3. Wiggle-test the lead at the gland; intermittent high-temp trips are usually the cable, not the element.

Symptoms & probable causes

• Nuisance high-temp trips
  Chafed lead, loose terminal, or a failing element drifting high.
• Temperature reads -40 or maximum
  Open or shorted sensor circuit.