SQUARE D
SQUARE D LR3D21L Overload Relay 12-18 A Trip Class 20 690V AC
Thermal overload relay protects 12 to 18 A motor circuits at 690 V AC with trip class 20 and auto or manual reset
- Protects motors from 12 A to 18 A overloads
- Trip class 20 delays nuisance trips on heavy starts
- Rated for 690 V AC three-phase supply
- Direct contactor mounting saves panel space and wiring
- Auto or manual reset restores operation fast
Overload Relay 12-18 A Trip Class 20
This Square D overload relay protects three-phase motors with a thermal trip mechanism rated for 690 V AC. It mounts directly to TeSys Deca contactors and offers an adjustable current range from 12 A to 18 A with Trip Class 20 timing. Screw clamp terminals accept standard wiring for straightforward installation in industrial control panels. The unit includes one normally open and one normally closed auxiliary contact for signalling or interlocking.
Suits panels needing adjustable thermal protection
Maintenance teams and panel builders who need a direct-mount relay for motors drawing between 12 A and 18 A will find this device fits the application. It is not suitable for circuits requiring a lower minimum setting or a higher maximum setting than the 12 A to 18 A range. Buyers needing electronic trip units, different trip classes, or DIN-rail mounting without a contactor should consider other relay styles.
Handles 12 A to 18 A loads at 690 V AC
The relay comfortably manages motor currents within the 12 A to 18 A adjustment window at voltages up to 690 V AC. Trip Class 20 provides a standard delay for typical motor starting profiles. It runs out of range for motors drawing less than 12 A or more than 18 A full-load current. The three-pole design covers all phases but offers no ground-fault or phase-loss detection beyond the thermal element.
Highlights
- Protects motors from 12 A to 18 A overloads
- Trip class 20 delays nuisance trips on heavy starts
- Rated for 690 V AC three-phase supply
- Direct contactor mounting saves panel space and wiring
- Auto or manual reset restores operation fast
Specifications
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Questions about this item
What contactor series must I already have to mount the LR3D21L directly?
The overload relay mounts directly to a TeSys Deca series contactor using its integral screw clamp terminals.
Will the 12–18 A range and Trip Class 20 protect an older motor that previously used a different trip class?
Trip Class 20 allows a longer acceleration time before tripping, so the motor must tolerate that delay; the 12–18 A dial must be set to the motor's full-load current.
How can I verify the LR3D21L is operating correctly after wiring?
Apply load current within the 12–18 A range; the relay should not trip at normal running current and the 1NO/1NC auxiliary contacts will change state only on an overload event.
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