SIEMENS
SIEMENS 3UB81234CW2 Overload Relay 3-12A Class 5/10/20/30
Adjustable 3 to 12 A overload relay with selectable trip classes 5, 10, 20, 30 and 690 V AC rating
- Adjustable 3–12 A range protects varied motor loads
- Four selectable trip classes match diverse starting profiles
- 690 V AC rating suits industrial power systems
- Direct contactor mounting simplifies panel assembly
- Screw terminals enable secure, tool-friendly wiring
Motor protection relay for industrial starters
The SIEMENS 3UB81234CW2 overload relay protects three-phase motors by monitoring current between 3 A and 12 A. It mounts directly to compatible contactors and suits Class 14 starters as well as Class 48 overload relay applications. Selectable trip classes 5, 10, 20 and 30 let the installer match the protection curve to the motor starting profile.
Thermal trip behaviour and power consumption
The thermal trip unit operates without external control voltage and draws only the minimal contactor coil power. Auto and manual reset modes are both available on the same unit, so the operator can choose automatic restart or supervised restart after a trip. The 690 V AC maximum rating covers standard industrial supply voltages without derating.
Screw terminals and direct contactor mounting
Three-pole screw terminals accept solid or stranded conductors for straightforward wiring in the panel. The direct-to-contactor mounting style eliminates separate DIN-rail hardware and keeps the starter assembly compact. One normally-open and one normally-closed auxiliary contact provide status signalling to the control circuit. Buyers who need a different current range or a separate mounting base cannot use this model.
Highlights
- Adjustable 3–12 A range protects varied motor loads
- Four selectable trip classes match diverse starting profiles
- 690 V AC rating suits industrial power systems
- Direct contactor mounting simplifies panel assembly
- Screw terminals enable secure, tool-friendly wiring
Specifications
| Brand | SIEMENS |
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Questions about this item
How is the overload relay mounted and which step is often missed?
The relay mounts directly to a compatible contactor using screw terminals; the step often missed is tightening each terminal to the specified torque so the 3 to 12 A trip range remains accurate.
What maintenance or replacement will the 3UB81234CW2 need over time?
The relay uses auto and manual reset with no separate thermal units to replace; periodic inspection of the 1NO/1NC auxiliary contacts and screw-terminal tightness is the only routine upkeep.
What limit appears first when the relay runs continuously at high load?
The 12 A maximum current setting and 690 V AC voltage rating define the thermal boundary; sustained operation above 12 A will cause the selected trip class 5, 10, 20 or 30 to operate first.
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