The Siemens 3RU2136-4QB0 is a SIRIUS 3RU2 thermal overload relay for motor protection, adjustable from 47 … 57 A, in size S2 for direct mounting on a SIRIUS 3RT2 contactor. It has 1 NO + 1 NC auxiliary contacts: the NC contact opens the contactor coil circuit on overload and the NO contact can signal the trip to the PLC.
The overload relay is the classic partner of a contactor in a motor starter. It is set to the motor rated current and can be reset manually or automatically after the motor has cooled down.
See our Siemens industrial controls for matching 3RT2 contactors in size S2.
Technical data
| Siemens order number | 3RU2136-4QB0 |
|---|---|
| Product | SIRIUS 3RU2 thermal overload relay |
| Size | S2 |
| Current setting range | 47 … 57 A |
| Trip class | CLASS 10 |
| Auxiliary contacts | 1 NO + 1 NC |
| Rated operating voltage | 690 V |
| Motor power at 400 V (approx.) | 30 kW |
| Mounting | Contactor mounting (size S2) |
| FLA, 3-phase motor at 480 V (UL) | 57 A |
| Power loss (hot, total) | 15.6 W |
| Ambient temperature (operation) | -40 … +70 °C |
| Dimensions (W x H x D) | 55 x 90 x 105 mm |
| Net weight | 0.321 kg |
| Condition | New, original Siemens |
Typical applications
- Star-delta starters (set to 0.58 x motor current in the phase leg)
- Replacement of an aged or damaged overload relay
- Motor starters with SIRIUS 3RT2 contactors
- Protection of motors with rated current 47 … 57 A
Compatibility and replacement
Plugs directly onto 3RT2 contactors of size S2 (3RT203x). For separate (stand-alone) mounting Siemens offers a terminal support. For electronic protection with a wider setting range Siemens offers the 3RB3 series.
Frequently asked questions
What motor size does it suit?
Per Siemens the range corresponds to about 30 kW at 400 V (AC-3), but always set it by the motor rated current, not by the kW rating.
How do I set it?
Turn the setting dial to the motor rated current from the nameplate, within 47 … 57 A.
What does CLASS 10 mean?
The trip class per IEC 60947-4-1: at 7.2 times the setting current the relay trips within 4 to 10 seconds, which suits motors with normal starting.
Do you ship to my country, and what is the warranty?
Yes. RendatSP ships worldwide from Yiwu, China, by air in 5 to 7 days once the part is ready, and every part carries a 1-year warranty. Send the order number and quantity on WhatsApp and we will reply with a quotation.
Before you order
Compare the complete order number on the old unit with this page, including the suffix: in most ranges the last characters set the coil voltage, current range or version. If the label is worn, send us a photo and we will identify the part.
RendatSP ships from Yiwu, China, to factories worldwide; air delivery usually takes 5 to 7 days once the part is ready. The part is new and original with a 1-year warranty (shipping, payment and warranty). For a quotation, message us on WhatsApp with the order number and quantity. We also have agents in Saudi Arabia, Iraq, the UAE, Egypt, Oman, Libya, Morocco, Mauritania, Yemen, Algeria and Jordan.
