SIEMENS
SIEMENS 3RU21264DB0 Overload Relay 20-25 A 690 V AC Trip Class 10
Thermal overload relay protects three-phase motors with a 20 to 25 A adjustable range, Trip Class 10 response and 690 V AC rating
- Thermal overload protection up to 25 A
- Trip Class 10 for standard motor starts
- Direct contactor mounting simplifies panel layout
- Screw terminals for secure field wiring
- 690 V AC rating covers industrial supplies
Overload Relay 20-25 A
The SIEMENS 3RU21264DB0 is a thermal overload relay designed to protect three-phase motors from excessive current. It mounts directly onto compatible SIRIUS series contactors with a frame size S0 footprint. The unit covers a setting range from 20 A minimum to 25 A maximum and operates at up to 690 V AC. Integrated 1NO/1NC auxiliary contacts provide status signalling for control circuits.
Trip Class 10 Upgrade
This relay replaces older thermal units that lack the faster Trip Class 10 response or direct contactor mounting. The jump is worth it when existing protection uses slower trip classes that allow longer overcurrent exposure. It also suits upgrades where screw-terminal wiring and built-in thermal units simplify installation. Auto and manual reset modes give flexibility for different recovery procedures.
690 V AC Interface Limits
The 690 V AC rating defines the maximum system voltage for safe operation; exceeding it voids protection coordination. Trip Class 10 suits standard motor starts but may nuisance-trip on high-inertia loads requiring longer acceleration. Three thermal elements must match the motor full-load current within the 20-25 A window. Screw terminals accept only solid or prepared stranded conductors within the relay's unnamed capacity.
Highlights
- Thermal overload protection up to 25 A
- Trip Class 10 for standard motor starts
- Direct contactor mounting simplifies panel layout
- Screw terminals for secure field wiring
- 690 V AC rating covers industrial supplies
Specifications
| Brand | SIEMENS |
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Questions about this item
How is the overload relay mounted to a contactor?
The relay uses direct-to-contactor mounting on the SIRIUS S0 frame; align the relay's main terminals with the contactor's load side and secure with the integrated mounting feet before wiring.
What is the correct sequence for setting the trip current and reset mode?
Set the adjustment dial between 20 A and 25 A to match the motor full-load current, then select auto or manual reset using the front selector before energising the circuit.
When should the internal thermal units be inspected or replaced?
Inspect the three included thermal units after any trip event or at scheduled maintenance intervals; replace them if discoloration, deformation, or a trip at the set current is observed.
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