What it is and what it does
The Siemens 3RU2116-1FJ0 is a SIRIUS thermal overload relay in the compact S00 frame size. It protects motors against overload and phase failure by monitoring current draw through a bimetallic strip that actuates a trip mechanism. The CLASS 10 designation means it will trip within 10 seconds at 7.2 times the current setting — fast enough to protect standard induction motors during a locked-rotor event without nuisance tripping during normal starting. Rated insulation voltage is 690 V, with AC-3e switching capability up to the same voltage. The auxiliary contact set is integrated — no add-on block needed — and carries ratings from 2 A at 24 V up to 3 A at 120 V and 1 A at 400 V, covering most PLC and contactor coil circuits.
Mounting and integration
This relay mounts directly onto a contactor — no DIN rail required. The fastening method is contactor mounting, which means it clips onto the front of a matching SIRIUS contactor and connects electrically through the main power terminals. The main current circuit uses M3 ring cable lugs, so expect to terminate with ring terminals rather than ferrules or bare wire. Mounting position is any, which simplifies panel layout. The S00 footprint is 45 mm wide, 76 mm tall, and 70 mm deep — small enough for crowded enclosures. Temperature compensation is active from -40 °C to +60 °C, so the trip curve stays accurate even in unheated plant environments.
Lifecycle and sourcing
RoHS compliance is documented with a substance prohibition date of October 1, 2009, covering the EU RoHS directive. The operating temperature range is -40 °C to +70 °C, with storage and transport tolerance from -55 °C to +80 °C.
What the ratings mean for fit
The auxiliary contact current ratings are given at specific voltages — 2 A at 24 V, 3 A at 120 V, 1 A at 400 V, and so on. These are the make/break capacities for the signal contacts, not the main power path. If you're switching a 24 VDC PLC input, the 2 A rating is more than adequate; at 400 VAC for a contactor coil, the 1 A rating handles it. The per-pole power dissipation is 2.2 W, which matters for thermal budgeting inside a sealed enclosure. The note "for message 'Tripped'" on the spec line refers to the auxiliary contact configuration that signals a trip condition to a PLC or HMI. This is a normally-closed or changeover contact that opens when the relay trips, giving a positive indication rather than relying on current sensing.