Product Description

Siemens 3RB3026-1NB0 Electronic Overload Relay – 0.32–1.25 A, Class 10E

The Siemens 3RB3026-1NB0 is a microprocessor-based electronic overload relay from the Siemens SIRIUS 3RB3 series, designed for reliable motor protection against overload, phase failure and asymmetry. The exact Siemens product data specifies an adjustable current range of 0.32 to 1.25 A, Class 10E, Size S0, contactor mounting, screw terminals for the main and auxiliary circuits, and manual/automatic reset. Siemens currently lists this article as an active product.

Important: The exact article 3RB3026-1NB0 is Class 10E, not Class 20E. Siemens' official product data and catalog identify this MLFB as 0.32–1.25 A, Class 10E, S0, contactor mounting.

Siemens SIRIUS 3RB3 Electronic Overload Relay

The 3RB3026-1NB0 belongs to the Siemens SIRIUS 3RB electronic overload relay family, designed for electronic monitoring and protection of motors in industrial electrical installations.

Its microprocessor-based electronic design continuously evaluates motor current and provides a defined Class 10E overload response. The compact S0 contactor-mounted design allows the relay to be integrated with compatible Siemens SIRIUS contactors in motor-starter assemblies.

Typical applications include:

• Small industrial motors

• Pumps

• Fans and blowers

• Small compressors

• Conveyors

• Machine tools

• Production equipment

• Process machinery

• Motor starters

• Industrial control panels

Adjustable 0.32–1.25 A Current Range

The 3RB3026-1NB0 provides an adjustable current-response range of 0.32 to 1.25 A, with a thermal current of 1.25 A. Siemens specifies a rated operational current of 1.25 A and an AC-3e operating current of 1.25 A at 400 V.

This makes the overload relay suitable for motors with relatively low rated currents.

The current setting should be adjusted according to the motor nameplate current and the requirements of the complete motor-protection system.

Class 10E Trip Characteristic

The exact 3RB3026-1NB0 is a Class 10E electronic overload relay. Siemens' official datasheet explicitly specifies CLASS 10E for this article.

Class 10E provides a defined overload tripping characteristic for motors with corresponding starting requirements. The selected trip class should be matched to the motor starting time and actual application conditions.

Electronic Overload Protection

The primary function of the 3RB3026-1NB0 is electronic protection against motor overload.

The relay continuously monitors motor current and responds when the configured overload characteristic is exceeded.

This helps protect compatible motors against:

• Prolonged overcurrent

• Excessive mechanical loading

• Motor overheating caused by overload

• Abnormal operating conditions

• Excessive starting duration

Correct current adjustment is essential for dependable motor protection.

Phase-Failure and Asymmetry Protection

The Siemens 3RB30 electronic overload relay family provides overload, phase-failure and asymmetry protection. These functions help protect three-phase motors against abnormal current conditions that can increase motor heating and electrical stress.

Phase-failure protection is particularly useful because operating a three-phase motor with a missing phase can cause unbalanced current and additional thermal stress.

1 NO + 1 NC Auxiliary Contacts

The 3RB3026-1NB0 provides 1 normally closed (NC) and 1 normally open (NO) auxiliary contact.

Siemens specifies the NC contact for contactor disconnection and the NO contact for the “tripped” message.

These contacts can be used for:

• Contactor-control circuits

• Trip indication

• Control-panel feedback

• Alarm signalling

• Motor fault indication

• Electrical interlocking

The auxiliary contacts provide a practical interface between the overload relay and the surrounding control circuit.

Contactor Mounting

The 3RB3026-1NB0 is designed for contactor mounting and belongs to Size S0. Siemens specifies the overload relay and compatible contactor size as S0.

This allows the relay to be combined with a compatible Siemens SIRIUS contactor to create a compact motor-starter assembly.

The exact contactor compatibility should be checked against the Siemens selection documentation before installation.

Screw-Terminal Connections

The 3RB3026-1NB0 uses screw-type terminals for both the main current circuit and auxiliary/control circuit. The auxiliary and control terminal is removable.

This provides a conventional wiring method for industrial electrical panels and motor-starter assemblies.

Manual and Automatic Reset

The exact 3RB3026-1NB0 supports manual and automatic RESET. Siemens specifies a typical recovery time of approximately 3 minutes with automatic reset, while manual and remote reset recovery are specified as 0 minutes under the applicable conditions.

The reset method should be selected according to the motor-control requirements and the safety considerations of the machine.

TEST Function and Self-Monitoring

The Siemens 3RB30 electronic overload relay range includes diagnostic features such as TEST functionality, switch-position indication and self-monitoring.

These features can assist with:

• Commissioning

• Functional testing

• Troubleshooting

• Preventive maintenance

• Panel servicing

Electrical Characteristics

The 3RB3026-1NB0 has an insulation voltage of 690 V and 6 kV surge-voltage resistance. Siemens specifies approximately 0.1 W total power loss at rated current in the hot operating state, or about 0.03 W per pole.

The relay is designed for 50–60 Hz operation and an operating ambient temperature range of -25 °C to +60 °C. Maximum installation altitude is specified as 2,000 m under the applicable conditions.

Motor Power Applications

Siemens gives the following guide motor-power ranges for the 3RB3026-1NB0:

• 0.12–0.37 kW at 400 V, 50 Hz

• 0.12–0.55 kW at 500 V, 50 Hz

• 0.18–0.75 kW at 690 V, 50 Hz

These are guide values; the actual motor starting and rated data must be considered when selecting the overload relay.

Industrial Motor Applications

Small Pumps

The relay can protect compatible low-current pump motors against overload, phase failure and asymmetry.

Fans and Blowers

The Class 10E characteristic can be used for motors with corresponding starting requirements.

Small Compressors

Electronic overload monitoring can help protect suitable compressor motors against excessive operating current.

Small Conveyors

The relay can be incorporated into compatible conveyor motor starters.

Machine Tools

Its compact S0 construction is suitable for machine-control panels and motor starters.

Production Equipment

The relay can be used for motor protection in suitable manufacturing and production machinery.

Suitable for OEMs, Panel Builders and Electrical Dealers

The 3RB3026-1NB0 is suitable for OEM equipment manufacturers, electrical panel builders, industrial maintenance teams, industrial buyers and electrical product dealers.

For customers purchasing through SB Smart, the product is positioned for industrial electrical product supply and procurement, rather than automation integration or automation-service work.

SB Smart can supply Siemens industrial electrical components for requirements across Faridabad, Delhi NCR, Gurgaon/Gurugram, Noida, Haryana, Punjab, Mumbai and other major Indian cities.

Key Features

• Siemens SIRIUS 3RB3 electronic overload relay

• Article number 3RB3026-1NB0

• Microprocessor-based electronic overload protection

• 0.32–1.25 A adjustable current range

• Class 10E

• Size S0

• Contactor mounting

• Screw terminals for main and auxiliary circuits

• 1 NO + 1 NC auxiliary contacts

• Overload protection

• Phase-failure protection

• Asymmetry protection

• Manual RESET

• Automatic RESET

• TEST function

• Self-monitoring

• Switch-position indication

• 690 V insulation voltage

• 6 kV surge-voltage resistance

Benefits

• 0.32–1.25 A adjustable range: Suitable for low-current industrial motors.

• Class 10E: Provides a defined overload characteristic for compatible motor-starting requirements.

• Electronic protection: Provides continuous motor-current monitoring.

• Phase protection: Helps protect against phase failure and asymmetry.

• 1 NO + 1 NC contacts: Provides control, signalling and trip-feedback functions.

• Contactor mounting: Supports compact S0 motor-starter assemblies.

• Screw terminals: Provides a familiar industrial wiring solution.

• Manual/automatic reset: Supports different motor-control requirements.

• TEST and self-monitoring: Assist commissioning and maintenance.

• Compact S0 design: Helps optimize control-panel space.

Why Choose Siemens 3RB3026-1NB0?

The Siemens 3RB3026-1NB0 is a compact electronic overload relay for motor protection in the 0.32–1.25 A range with a Class 10E trip characteristic.

Its combination of electronic overload protection, phase-failure and asymmetry protection, S0 contactor mounting, 1 NO + 1 NC auxiliary contacts, screw connections and manual/automatic reset makes it suitable for small industrial motor starters, OEM machinery, electrical panels and replacement requirements. Siemens currently lists the article as an active product.

For SB Smart, this product should be positioned around Siemens industrial electrical product supply, dealer/distributor procurement and nationwide industrial component sourcing, without claiming automation integration services.

Delivery Across India

SB Smart supplies Siemens industrial electrical products across Faridabad, Gurgaon/Gurugram, Delhi NCR, Haryana, Noida, Punjab, Mumbai and major cities across India.

Major delivery locations include:

• Faridabad

• Delhi

• Gurgaon/Gurugram

• Delhi NCR

• Noida

• Greater Noida

• Haryana

• Punjab

• Mumbai

• Pune

• Ahmedabad

• Bengaluru

• Hyderabad

• Chennai

• Kolkata

• Jaipur

• Chandigarh

• Lucknow

• Indore

• Surat

• Vadodara

• Nagpur

• Coimbatore

• And other major cities across India

Frequently Asked Questions

1. What is Siemens 3RB3026-1NB0?

It is a Siemens SIRIUS 3RB3 electronic overload relay for motor protection with a 0.32–1.25 A adjustable current range and Class 10E trip characteristic.

2. What is the current setting range?

The adjustable current range is 0.32–1.25 A.

3. What is the trip class?

The exact 3RB3026-1NB0 is Class 10E, not Class 20E.

4. Does it provide phase-failure protection?

Yes. The Siemens 3RB30 range provides phase-failure and asymmetry protection in addition to overload protection.

5. How many auxiliary contacts does it have?

It provides 1 NO + 1 NC auxiliary contacts. The NC contact is specified for contactor disconnection and the NO contact for the “tripped” indication.

6. Is it contactor-mounted?

Yes. The 3RB3026-1NB0 is designed for S0 contactor mounting.

7. Does it use screw terminals?

Yes. Siemens specifies screw-type terminals for both the main and auxiliary circuits.

8. What reset options are available?

It supports manual and automatic RESET.

9. Does it have diagnostic functions?

Yes. The 3RB30 family includes TEST functionality, switch-position indication and self-monitoring.

10. Where can I buy Siemens 3RB3026-1NB0 in India?

SB Smart supplies Siemens industrial electrical products in India, including SIRIUS electronic overload relays and related motor-protection components for industrial buyers, panel builders, maintenance requirements and product procurement.