Skip to main content
Kara TejaratMehr Aein
Search
رله حرارتی زیمنس SIRIUS 3RU2، مدل 3RU2126-4FB0 سایز S0، نمای روبه‌رو

© Siemens AG

siriusSeries 3RU/3RBActive

SIRIUS 3RU thermal and 3RB electronic overload relays

SIRIUS 3RU / 3RB overload relays

Siemens 3RU2 thermal and 3RB3 electronic overload relays that mount directly under a 3RT contactor; sizes S00 to S3 and a setting range of 0.1 A to 115 A

Request this product

Price and delivery time are given after a technical review.

Overview

Overview

An overload relay measures the motor current and, when an overload, a phase asymmetry or a phase failure would heat the load beyond its limit, releases the contactor through its own auxiliary contact. It is not a power switch and does not clear short circuits. SIRIUS has two working principles: the 3RU2 is a thermal relay with bimetal strips, and the 3RB3 (that is 3RB30 and 3RB31) is an electronic relay with built-in current transformers and solid-state circuits. Both sit directly under a 3RT2 contactor or are mounted on their own with a terminal support.

Read more

Difference between 3RU and 3RB

The 3RU2 works on bimetal heating, has a fixed CLASS 10 trip class (size S2: CLASS 10 or 10A) and is meant for loads with normal starting. Only the 3RU2 can protect DC loads and single-phase AC loads against overload, and it compensates the ambient temperature from -40 to +60 degrees C. The 3RB30 does the same job electronically, with a fixed CLASS 10E or 20E. The 3RB31 has an adjustable trip class (5E, 10E, 20E and 30E) and also internal ground-fault detection and an electrical remote reset. For heavy and long starts, a 3RB is the choice.

The setting range of a 3RB is wide (1:4, for example 3 to 12 A or 6 to 25 A), so fewer codes cover all currents and stock keeping is simpler. Power loss is lower too: in size S0 at 40 A the data sheet gives 9.6 W for the 3RU2126-4FB0 and only 3 W for the 3RB3026-1VB0. In return, a 3RB protects only three-phase loads on a sinusoidal 50/60 Hz supply, and its temperature compensation runs from -25 to +60 degrees C. The dimensions of the 3RB30/3RB31 are about those of the 3RU21, so replacing one with the other is easy.

Sizes and range

The 3RU2 comes in four sizes: S00 from 0.11 to 16 A, S0 up to 40 A, S2 up to 80 A and S3 up to 100 A. The 3RB30 and 3RB31 cover 0.1 to 115 A in the same four sizes; size S3 reaches 115 A with 3RB3046-1XB0. The widths are 45, 45, 55 and 70 mm, and the motor power at 400 V reaches 45 kW with the 3RU2 and 55 kW with the 3RB3. Above that, 3RB20 and 3RB21 provide sizes S6 to S12 from 50 to 630 A, and 3RB22, 3RB23 and 3RB24 (with IO-Link) work with a current measuring module up to 630 A.

Beside 3RT and 3RV

The overload relay is matched electrically and mechanically to the 3RT2 contactor and connects to it directly. Short circuits must be cleared by fuses or by a 3RV23 motor starter protector, which takes short-circuit protection only. If a 3RV20 is used, which has its own overload release, no separate relay is needed. The advantage of the fuse, contactor and overload relay arrangement is that overload and short-circuit trips are signalled separately and that, in networks above 400 V, the breaking capacity of the fuses, above 100 kA, is kept.

Features

  • 3RU2: thermal bimetal relay from 0.11 A to 100 A
  • 3RB30 and 3RB31: electronic relay from 0.1 A to 115 A
  • Four sizes S00, S0, S2 and S3, 45, 45, 55 and 70 mm wide
  • Trip class: 3RU2 CLASS 10 (CLASS 10 or 10A in S2), 3RB30 fixed CLASS 10E or 20E, 3RB31 adjustable 5E to 30E
  • Sensitive to phase failure and phase asymmetry in both series
  • Internal ground-fault detection in the 3RB31
  • Manual or automatic reset; remote reset by an add-on module or, in the 3RB31, built in
  • Direct mounting under a 3RT2 contactor or stand-alone with a terminal support

Advantages

  • 3RB: a wide 1:4 setting range that reduces the number of codes in stock
  • 3RB: lower power loss; 3 W against 9.6 W for the 3RU2 in size S0 at 40 A
  • 3RB30/3RB31: heavy starting with CLASS 20E or 30E; 3RU2: protection of DC and single-phase loads
  • The 3RB30/3RB31 is about the size of the 3RU21, so it can replace it without changes in the cabinet

Models and codes

Models and codes
ModelOrder codeCode typeAttributesRequest
3RU2116-1HB0, size S00رلهٔ حرارتی 3RU2، S00، محدودهٔ تنظیم ۵٫۵ تا ۸ آمپر، CLASS 10، ریست دستی/خودکار؛ موتور ۳ کیلووات در ۴۰۰ ولت3RU2116-1HB0Exact code
Size:
S00
Type:
3RU2 thermal
Setting range:
5.5 ... 8 A
Trip class:
CLASS 10
Motor power AC-3 (400 V):
3 kW
Terminals:
Screw (main and auxiliary)
Request 3RU2116-1HB0, size S00
3RU2126-4FB0, size S0رلهٔ حرارتی 3RU2، S0، ۳۴ تا ۴۰ آمپر، CLASS 10؛ بالاترین پنجرهٔ S0؛ موتور ۱۸٫۵ کیلووات در ۴۰۰ ولت، تلفات ۹٫۶ وات3RU2126-4FB0Exact code
Size:
S0
Type:
3RU2 thermal
Setting range:
34 ... 40 A
Trip class:
CLASS 10
Motor power AC-3 (400 V):
18.5 kW
Terminals:
Screw (main and auxiliary)
Request 3RU2126-4FB0, size S0
3RU2136-4RB0, size S2رلهٔ حرارتی 3RU2، S2، ۷۰ تا ۸۰ آمپر، CLASS 10A؛ موتور ۳۷ کیلووات در ۴۰۰ ولت3RU2136-4RB0Exact code
Size:
S2
Type:
3RU2 thermal
Setting range:
70 ... 80 A
Trip class:
CLASS 10A
Motor power AC-3 (400 V):
37 kW
Terminals:
Screw (main and auxiliary)
Request 3RU2136-4RB0, size S2
3RU2146-4MB0, size S3رلهٔ حرارتی 3RU2، S3، ۸۰ تا ۱۰۰ آمپر، CLASS 10، ولتاژ کاری ۱۰۰۰ ولت؛ بالاترین کد 3RU2؛ موتور ۴۵ کیلووات در ۴۰۰ ولت3RU2146-4MB0Exact code
Size:
S3
Type:
3RU2 thermal
Setting range:
80 ... 100 A
Trip class:
CLASS 10
Motor power AC-3 (400 V):
45 kW
Terminals:
Screw (main and auxiliary)
Request 3RU2146-4MB0, size S3
3RB3016-1SB0, size S00رلهٔ الکترونیکی 3RB30، S00، ۳ تا ۱۲ آمپر (۱ به ۴)، CLASS 10E؛ موتور ۱٫۵ تا ۵٫۵ کیلووات در ۴۰۰ ولت3RB3016-1SB0Exact code
Size:
S00
Type:
3RB30 electronic
Setting range:
3 ... 12 A
Trip class:
CLASS 10E
Motor power AC-3 (400 V):
1.5 ... 5.5 kW
Terminals:
Screw (main and auxiliary)
Request 3RB3016-1SB0, size S00
3RB3026-1QB0, size S0رلهٔ الکترونیکی 3RB30، S0، ۶ تا ۲۵ آمپر، CLASS 10E؛ موتور ۳ تا ۱۱ کیلووات در ۴۰۰ ولت3RB3026-1QB0Exact code
Size:
S0
Type:
3RB30 electronic
Setting range:
6 ... 25 A
Trip class:
CLASS 10E
Motor power AC-3 (400 V):
3 ... 11 kW
Terminals:
Screw (main and auxiliary)
Request 3RB3026-1QB0, size S0
3RB3026-1VB0, size S0رلهٔ الکترونیکی 3RB30، S0، ۱۰ تا ۴۰ آمپر، CLASS 10E؛ موتور ۵٫۵ تا ۱۸٫۵ کیلووات در ۴۰۰ ولت، تلفات ۳ وات3RB3026-1VB0Exact code
Size:
S0
Type:
3RB30 electronic
Setting range:
10 ... 40 A
Trip class:
CLASS 10E
Motor power AC-3 (400 V):
5.5 ... 18.5 kW
Terminals:
Screw (main and auxiliary)
Request 3RB3026-1VB0, size S0
3RB3036-1UB0, size S2رلهٔ الکترونیکی 3RB30، S2، ۱۲٫۵ تا ۵۰ آمپر، CLASS 10E؛ موتور ۷٫۵ تا ۲۲ کیلووات در ۴۰۰ ولت3RB3036-1UB0Exact code
Size:
S2
Type:
3RB30 electronic
Setting range:
12.5 ... 50 A
Trip class:
CLASS 10E
Motor power AC-3 (400 V):
7.5 ... 22 kW
Terminals:
Screw (main and auxiliary)
Request 3RB3036-1UB0, size S2
3RB3046-1UB0, size S3رلهٔ الکترونیکی 3RB30، S3، ۱۲٫۵ تا ۵۰ آمپر، CLASS 10E، ولتاژ کاری ۱۰۰۰ ولت3RB3046-1UB0Exact code
Size:
S3
Type:
3RB30 electronic
Setting range:
12.5 ... 50 A
Trip class:
CLASS 10E
Motor power AC-3 (400 V):
7.5 ... 22 kW
Terminals:
Screw (main and auxiliary)
Request 3RB3046-1UB0, size S3
3RB3046-1XB0, size S3رلهٔ الکترونیکی 3RB30، S3، ۳۲ تا ۱۱۵ آمپر، CLASS 10E؛ بالاترین کد 3RB3 ثبت‌شده؛ موتور ۱۸٫۵ تا ۵۵ کیلووات در ۴۰۰ ولت3RB3046-1XB0Exact code
Size:
S3
Type:
3RB30 electronic
Setting range:
32 ... 115 A
Trip class:
CLASS 10E
Motor power AC-3 (400 V):
18.5 ... 55 kW
Terminals:
Screw (main and auxiliary)
Request 3RB3046-1XB0, size S3
3RB3123-4QE0, size S0, 3RB31رلهٔ الکترونیکی 3RB31، S0، ۶ تا ۲۵ آمپر، کلاس قابل تنظیم 5 تا 30، تشخیص خطای زمین داخلی، ترمینال فنری؛ موتور ۳ تا ۱۱ کیلووات در ۴۰۰ ولت3RB3123-4QE0Exact code
Size:
S0
Type:
3RB31 electronic
Setting range:
6 ... 25 A
Trip class:
CLASS 5 ... 30 (adjustable)
Motor power AC-3 (400 V):
3 ... 11 kW
Terminals:
Spring-type (main and auxiliary)
Ground-fault detection:
Internal
Request 3RB3123-4QE0, size S0, 3RB31
3RB2056-1FC2, size S6رلهٔ الکترونیکی 3RB20، S6، ۵۰ تا ۲۰۰ آمپر، CLASS 10E، اتصال باسبار در مدار قدرت3RB2056-1FC2Exact code
Size:
S6
Type:
3RB20 electronic
Setting range:
50 ... 200 A
Trip class:
CLASS 10E
Terminals:
Busbar (main), screw (auxiliary)
Request 3RB2056-1FC2, size S6
Show 1 more model
Models and codes
ModelOrder codeCode typeAttributesRequest
3RB2066-1GC2, size S10/S12رلهٔ الکترونیکی 3RB20، S10/S12، ۵۵ تا ۲۵۰ آمپر، CLASS 10E، اتصال باسبار در مدار قدرت3RB2066-1GC2Exact code
Size:
S10/S12
Type:
3RB20 electronic
Setting range:
55 ... 250 A
Trip class:
CLASS 10E
Terminals:
Busbar (main), screw (auxiliary)
Request 3RB2066-1GC2, size S10/S12

Technical specifications

Check the specifications against the data sheet of the exact code before ordering.
مشخصات عمومی
SizesSizesS00, S0, S2, S3 (3RU2, 3RB30, 3RB31); S6 … S12 (3RB20, 3RB21); S00 … S12 (3RB22 … 3RB24)
Width by sizeWidth by sizeS00 45 mm, S0 45 mm, S2 55 mm, S3 70 mm (S6 120 mm, S10/S12 145 mm)
Current range of the 3RU2Current range of the 3RU20.11 … 100 A
Current range of the 3RB30 and 3RB31Current range of the 3RB30 and 3RB310.1 … 115 A
Motor power at 400 V, sizes S00 to S2Motor power at 400 V, sizes S00 to S20.04 … 37 kW
Motor power at 400 V, size S3Motor power at 400 V, size S33RU2: up to 45; 3RB3: up to 55 kW
حفاظت و عملکرد
Operating principleOperating principle3RU2: bimetal (thermal); 3RB30 / 3RB31: current transformers and solid-state electronics
Trip classTrip class3RU2: CLASS 10 (S2: CLASS 10 or 10A); 3RB30: CLASS 10E or 20E (fixed); 3RB31: CLASS 5E, 10E, 20E, 30E (adjustable)
Setting range ratio of the 3RB30 and 3RB31Setting range ratio of the 3RB30 and 3RB311:4
Phase failure and phase asymmetry protectionPhase failure and phase asymmetry protection3RU2 and 3RB30/3RB31
Internal ground-fault detectionInternal ground-fault detection3RB31 only (can be activated)
Protection of DC and single-phase AC loadsProtection of DC and single-phase AC loads3RU2 only
ResetResetManual / automatic selector; remote reset: 3RU2 by mechanical or electrical module, 3RB30 by mechanical module, 3RB31 electrical (built in)
مدار قدرت و فرمان
Power loss of 3RU2126-4FB0 (S0, 34 to 40 A), hot at rated currentPower loss of 3RU2126-4FB0 (S0, 34 to 40 A), hot at rated current9.6 W
Power loss of 3RB3026-1VB0 (S0, 10 to 40 A), hot at rated currentPower loss of 3RB3026-1VB0 (S0, 10 to 40 A), hot at rated current3 W
Rated operational voltage, S00 to S2Rated operational voltage, S00 to S2690 V AC, 50 / 60 Hz
Rated operational voltage, S3Rated operational voltage, S31000 V
Auxiliary contactsAuxiliary contacts1 NO (tripped message) + 1 NC (contactor disconnection)
شرایط محیطی و اتصال
Temperature compensationTemperature compensation3RU2: -40 … +60; 3RB30/3RB31: -25 … +60 °C
Current derating factor of the 3RU2 at 70 °CCurrent derating factor of the 3RU2 at 70 °C0.87 … 0.94 depending on size and current (for example 0.87 for S00 and S0 up to 20 A)
Connection systemsConnection systemsScrew; spring-loaded (S00 and S0; S2 auxiliary circuit only); ring cable lug (3RU2 only, S00 and S0)

Modules and accessories

  • Terminal support for stand-alone assembly

    Terminal support for stand-alone mounting on a 35 mm rail or with screws; screw-type and spring-loaded in S00 and S0, screw-type in S2

  • Mechanical remote reset (release slide and cable release)

    Release slide and cable release for mechanical remote reset, compatible with all sizes

  • Module for electrical remote reset (3RU2)

    Electrical remote reset module for the 3RU2 only, for 24 to 30 V, 110 to 127 V or 220 to 250 V AC/DC

  • Terminal cover for ring cable lug connections

    Terminal cover for ring cable lug connections, compatible with all sizes

  • Sealable cover

    Sealable transparent cover that stops the current setting from being tampered with, for S00, S0 and S2

Documents

Official manufacturer links

Applications

  • Protecting three-phase motors with normal starting with the 3RU2
  • Motors with a long starting time (heavy starting) with the 3RB30 in CLASS 20E or with the 3RB31
  • Protecting DC and single-phase AC loads with the 3RU2
  • Fused feeders and networks above 400 V
  • Direct-on-line, reversing and star-delta starters

Frequently asked questions

3RU or 3RB: which one should be chosen?

For a motor with normal starting, and where DC or single-phase AC loads are also involved, the 3RU2 bimetal relay. For heavy and long starts (CLASS 20E or 30E), a wide 1:4 setting range with fewer codes, lower power loss, or ground-fault detection, the 3RB electronic relay: the 3RB30 with a fixed class and the 3RB31 with an adjustable class and ground-fault detection. Both series reach sizes S00 to S3 and have about the same dimensions.

What do CLASS 10, 10A, 10E, 20E and 30E mean?

The trip class states when the relay must trip at 7.2 times the set current from the cold state: CLASS 10A between 2 and 10 seconds, CLASS 10 between 4 and 10, CLASS 20 between 6 and 20 and CLASS 30 between 9 and 30 seconds. The letter E means electronic. The 3RU2 is for normal starting in CLASS 10 or 10A; the 3RB30 is fixed at 10E or 20E and the 3RB31 adjustable between 5E, 10E, 20E and 30E for heavy starting.

Does the relay mount directly on the 3RT contactor?

Yes. The 3RU2 and 3RB3 are matched electrically and mechanically to the 3RT2 and mount directly under the contactor with connection pins; stand-alone mounting on a rail with a terminal support is also possible. The relay size must fit the contactor size, and the data sheet of each code states the contactor size it can be combined with, for example S00 for 3RU2116-1HB0.

What if the current is above 100 A?

According to the 2019 Siemens catalogue, the 3RB20 and 3RB21 provide sizes S6 to S12 from 50 to 630 A (examples: 3RB2056-1FC2 with 50 to 200 A and 3RB2066-1GC2 with 55 to 250 A, both CLASS 10E with busbar connection). The 3RB22, 3RB23 and 3RB24 go up to 630 A with a current measuring module, and the 3RB24 has IO-Link.

What happens when the ambient temperature exceeds 60 degrees C?

The 3RU21 is temperature-compensated up to 60 degrees C. Between 60 and 70 degrees C the permitted current has to be multiplied by a factor f (Imax = Ie x f). At 70 degrees C the factor is between 0.87 and 0.94 depending on size and current; for example 0.87 for S00 and S0 up to 20 A and 0.94 for 22 to 32 A. According to the manual, the 3RB30/3RB31 compensates from -25 to +60 degrees C.

Does an overload relay also clear short circuits?

No. The overload relay only releases the contactor. Short circuits have to be cleared by fuses or a motor starter protector; with a 3RV20, which has an overload release, no separate relay is needed, and with a 3RV23, which takes short-circuit protection only, a 3RB or 3RU goes beside it.

Related products

  • کنتاکتور زیمنس SIRIUS 3RT20 سایز S0 با ترمینال پیچی، نمای سه‌رخ از جلو
    3RTActive

    SIRIUS 3RT power contactors

    SIRIUS 3RT power contactors

    Siemens three-pole power contactors for switching motors, from size S00 to S12 and up to 250 kW at 400 V, with AC, DC and AC/DC coils

    کنترل و حفاظت موتور

  • کلید حرارتی/محافظ موتور (MPCB) زیمنس SIRIUS 3RV2، مدل 3RV2021-4DA10 سایز S0، نمای روبه‌رو
    3RVActive

    SIRIUS 3RV motor starter protectors (MPCB)

    SIRIUS 3RV motor starter protectors

    Siemens motor starter protector (MPCB) with overload and short-circuit protection in one device; sizes S00 to S3, setting range 0.11 A to 100 A, motors up to 45 kW

    کنترل و حفاظت موتور

  • رله ترمیستوری حفاظت موتور زیمنس SIRIUS 3RN2، مدل‌های 3RN2023 و 3RN2010، نمای سه‌رخ
    3RN2Active

    SIRIUS 3RN2 thermistor motor protection relay

    SIRIUS 3RN2

    Siemens thermistor relay for direct motor protection with PTC sensors in the winding, in 17.5 mm and 22.5 mm widths, with a 24 to 240 V AC/DC supply and ATEX-approved versions

    کنترل و حفاظت موتور

  • رله مانیتورینگ جریان زیمنس SIRIUS 3UG4822 با نمایشگر و IO-Link، نمای سه‌رخ
    3UGActive

    SIRIUS 3UG monitoring relays

    SIRIUS 3UG

    Siemens monitoring relays for phase, voltage and current control: phase sequence and failure, asymmetry, frequency, under- and overvoltage, current and power, insulation resistance and DC loads; most models 22.5 mm wide

    کنترل و حفاظت موتور

Need SIRIUS 3RU thermal and 3RB electronic overload relays?

Send your order code or requirement; after a technical review we give you the price and delivery time.

Request this product