Siemens, SIRIUS 3RU2 Thermal Overload Relay 1 NO/1 NC, Trip Dial: 1.8 → 2.5 A, 1.8A, 2.5 A F.L.C, 2.5A Contact Rating,

RS Stock No.:: 706-1601
Mfr. Part No.:: 3RU2126-1CB0
Manufacturer:: Siemens

Siemens, SIRIUS 3RU2 Thermal Overload Relay 1 NO/1 NC, Trip Dial: 1.8 → 2.5 A, 1.8A, 2.5 A F.L.C, 2.5A Contact Rating,

Subtotal (1 unit)*

SGD178.82

(exc. GST)

SGD194.91

(inc. GST)

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Plus 19 unit(s) shipping from 12 October 2026

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Units	Per unit
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*price indicative

RS Stock No.:: 706-1601
Mfr. Part No.:: 3RU2126-1CB0
Manufacturer:: Siemens

Specifications

Technical data sheets

Legislation and Compliance

Product Details

Find similar products by selecting one or more attributes.

Select all	Attribute	Value
	Brand	Siemens
	FLC Motor Rating	1.8A, 2.5A
	Product Type	Thermal Overload Relay
	Relay Contact Current	2.5A
	Series	SIRIUS 3RU2
	Mount Type	Direct
	Power Rating	1.5kW
	Pole and Throw Configuration	3P
	Normal State Configuration	1 NO/1 NC
	Terminal Type	Screw
	IP Rating	IP20
	Reset Method	Automatic & Manual
	Number of Auxiliary Contacts	2
	Width	45mm
	Minimum Operating Temperature	-40°C
	Adjustable Current Range	1.8 → 2.5 A
	Length	87mm
	Maximum Operating Temperature	70°C
	Contact Voltage	690V ac
	Depth	73mm
	Standards/Approvals	IEC, EAC, WEEE (2012/19/EU), REACH, CE, UKCA, RoHS, UL, CCC

	Select all
	Brand Siemens
	FLC Motor Rating 1.8A, 2.5A
	Product Type Thermal Overload Relay
	Relay Contact Current 2.5A
	Series SIRIUS 3RU2
	Mount Type Direct
	Power Rating 1.5kW
	Pole and Throw Configuration 3P
	Normal State Configuration 1 NO/1 NC
	Terminal Type Screw
	IP Rating IP20
	Reset Method Automatic & Manual
	Number of Auxiliary Contacts 2
	Width 45mm
	Minimum Operating Temperature -40°C
	Adjustable Current Range 1.8 → 2.5 A
	Length 87mm
	Maximum Operating Temperature 70°C
	Contact Voltage 690V ac
	Depth 73mm
	Standards/Approvals IEC, EAC, WEEE (2012/19/EU), REACH, CE, UKCA, RoHS, UL, CCC

COO (Country of Origin):: DE

Siemens 3RU2 Series Thermal Overload Relay, 1.8 to 2.5A Adjustable Current Range, 1.5kW Power Rating - 3RU2126-1CB0

This thermal overload relay provides adjustable motor protection for three-phase circuits, detecting overloads and signalling trips for control systems. It is designed for direct mounting with screw connections and supports both manual and automatic reset modes, making it suitable for industrial control panels operating in a wide ambient temperature range.

Features & Benefits

• Adjustable current range 1.8 to 2.5A for precise motor protection
• Trip class 10 minimises nuisance trips for intermittent loads
• Rated operational voltage up to 690V for high-voltage systems
• Integrated auxiliary switch with 1 NO and 1 NC for status signalling
• Auxiliary contact currents rated to 3A at low voltages for control reliability
• IP20 front protection for safe finger-safe operation

Applications

• Suitable for protecting small three-phase motors up to 1.5 kW
• Ideal for use with contactors in industrial control panels
• Used with automation systems requiring overload feedback
• Can be used for motor starter assemblies in HVAC equipment
• Suitable for installations exposed to -40 to 70 °C ambient temperatures

How is the device connected to the main and auxiliary circuits?

Main and auxiliary circuits use screw-type terminals with top-and-bottom wiring for the main conductors and separate screws for auxiliaries.

What conductor sizes can be terminated on the main contacts?

Main contacts accept solid or stranded conductors from 1mm² up to 10 mm², including provisions for two conductors per Terminal where specified.

What electrical endurance can be expected for the auxiliary contacts?

Auxiliary contacts are rated for AC-15 switching with currents up to 3A at 24 to 125V and lower permissible currents at higher voltages, with contact rating B600/R300.

How is short-circuit protection for the auxiliary switch achieved?

Recommended protection for the auxiliary circuit uses gG fuses at 6A or fast fuses at 10A as specified for short-circuit protection.

Note

Screw Terminals can only be used with screw Terminal overloads and spring Terminals can only be used with spring Terminal overloads.

Approvals

CE, UL, CSA