Oil level sensor / switch

Float, capacitive or optical sensor that trips or warns on low sump oil level.

Usually closed with correct oil level; opens on low (fail-safe). Confirm per machine — some are reversed.

How it works

A float reed switch, capacitive probe or optical prism in the sump wall changes state when oil falls below the safe level. Most controllers alarm first and trip on continued low level.

Specifications

Contact rating

Pilot duty, typically 0.5 – 1 A @ 24 – 240 V

Reed switch resistance

< 1 Ω closed, OL open

Parts you can order

• Generic industrial

  Sump oil level switch

  By stem length and float

  $60 – $240

Field test procedure

1. With correct level and machine locked out, ohm the switch: NC type should read < 1 Ω.
2. Foam from the wrong oil or an over-full sump makes a good sensor chatter.

Symptoms & probable causes

• Low oil alarm with a full sight glass
  Failed sensor, foaming oil, or a shorted lead.