Siemens 3RV2021 MPCB 0.7–40 A

The Siemens 3RV2021 is a motor protection circuit breaker with a 0.7–40 A adjustable setting range. It combines motor switching, overload protection, short-circuit protection and phase-failure sensitivity in one compact device, and can be combined with a contactor to build a complete DOL or star-delta starter. Several setting ranges are available under this listing.

Key features

Adjustable thermal overload setting matched to the motor nameplate current
Magnetic short-circuit protection
Phase-loss sensitivity to protect motors from single phasing
Rotary/push handle with trip indication and padlocking
Auxiliary contacts, undervoltage releases and enclosures available

Technical specifications

Brand	Siemens
Part number / model	3RV2021
Device type	Motor protection circuit breaker / manual motor starter
Current setting range	0.7–40 A
Poles	3P
Protection	adjustable thermal overload + magnetic short-circuit + phase-loss sensitivity
Rated voltage	up to 690 V AC
Standard	IEC/EN 60947-2, IEC/EN 60947-4-1

Available versions

Current Range: 0.7-1 A, 1.1-1.6 A, 1.4-2 A, 1.8-2.5 A, 2.2-3.2 A, 2.8-4 A, 3.5-5 A, 4.5-6.3 A, 5.5-8 A, 7-10 A, 9-12 A, 11-16 A, 13-20 A, 16-22 A, 18-25 A, 23-28 A, 27-32 A, 34-40 A, 30-36 A.

Typical applications

Water pumps and booster pump panels
Fans, compressors and conveyors
HVAC units and cooling towers
Machine tools and MCC panels

Selection and installation tips

Choose the setting range so that the motor full-load current (from the nameplate) lies inside it, then set the dial exactly to that current. Typical: 1.5 kW 400 V ≈ 3.5 A, 4 kW ≈ 8.5 A, 7.5 kW ≈ 15 A, 15 kW ≈ 29 A.

Frequently asked questions

Do I still need an overload relay with an MPCB?

No – a standard MPCB already includes adjustable thermal overload protection. Only magnetic-only versions need a separate overload relay.

Can an MPCB start the motor directly?

Yes, it can switch the motor manually; for remote or automatic control combine it with a contactor.

Buy Siemens 3RV2021 in Egypt

Order the Siemens 3RV2021 motor protection circuit breaker (MPCB) from Spark Egypt and receive a genuine product with an official tax invoice. We deliver to Cairo, Giza, New Cairo, 6th of October, Sheikh Zayed, the New Administrative Capital, Alexandria, the Delta, the Canal cities and Upper Egypt, and our engineers help contractors, installers and maintenance teams check ratings, accessories and cross-references before purchase. Request a quotation for bulk or project quantities.