LEFOO LF12 Three-Phase Air Compressor Pressure Switch
Three-phase compressor pressure control in the LEFOO LF12 family. The correct operating range, contact wiring and hydraulic or pneumatic installation depend on the ordered variant.
Model Identification & Key Specifications
Manufacturer Technical Data
Three-phase multipole NC switch offers motor thermal relay options and an unloaded compressor start valve. OEM table varies ratings dramatically: 400VAC 7.5A/11A and 690VAC 4.5A/6.5A options rather than one universal three-phase rating. Manufacturer says thermal overload relay may require 30-minute cooldown and motor cycling interval above five minutes. The cited CE document concerns the 2014/35/EU low-voltage requirements for its stated scope.
AirAlign Engineering & Selection Analysis
The thermal relay protects against overheating only as specified for the chosen motor configuration. A manual reset or cooling delay can change restart behaviour, so the switch must not be treated as a generic three-pole mains isolator.
Correct system operation is determined by the restart threshold, stop threshold, motor electrical duty and the available pressure supply. An adjustment range does not imply every combination is approved: compare manufacturer-specified differential, pressure proof, operating medium and fitting. For motor-driven equipment, locked-rotor conditions, overload protection and cycling frequency are separately important even where a contact-current rating is published.
Installation, Compatibility & Protection
Specify both cut-in and cut-out conditions for the intended equipment, and verify the manufacturer’s permitted hysteresis. Do not use proof or burst pressures as running thresholds.
NO and NC contacts have different protection and restart behavior. Match the wiring schedule and motor/contactor duty, rather than relying only on voltage and ampere numbers.
Verify actual air versus water compatibility, wetted materials, connection thread standard, sealing method and temperature of the process. The manufacturer variant must support the full application.
Manufacturer certificates and conformity documents should be interpreted only for the models and revisions explicitly covered.
LF12 Three-Phase Motor Selection: Practical Checks
LF12 is not just an air-pressure switch with an extra terminal. LEFOO specifies multiple contact ratings for different motor supply configurations. A three-phase nameplate alone does not establish the electrical load that the delivered switch can safely interrupt.
| Supply / application | Manufacturer-listed alternatives | What to check |
|---|---|---|
| Single phase | 120 or 230 VAC: 10 A | Check installed motor and starting method. |
| Three phase, 400 VAC | 7.5 A or 11 A options | Confirm the exact version, not the higher of two ratings by default. |
| Three phase, 500 VAC | 6 A or 9 A options | Verify contact/motor combination and wiring diagram. |
| Three phase, 690 VAC | 4.5 A or 6.5 A options | Do not extrapolate a 400 VAC value to 690 VAC. |
| Thermal overload relay | Optional accessory/variant | Match motor setting, fault response and maker reset/cooldown instructions. |
Evidence: LEFOO LF12 rated contact and motor-control options. Factory setpoints, connector arrangement, thermal relay setting and model certification must be resolved by order suffix.
Related Models & AirAlign Categories
LEFOO LF15 Air Compressor Switch · LEFOO LF18 Three-Phase Pressure Switch · Pressure Switches · LEFOO manufacturer profile
Official Manufacturer Sources
Original maker catalogue evidence used for the model values above. Review the latest datasheet, ordering chart and approval scope for the specific suffix.
LF12 — three-phase motor switching coordination
LF12 is a three-phase compressor pressure switch family; motor circuit coordination must match contact ratings, phase voltage, overload protection and starter contactors. A pressure limit does not replace motor thermal overload or short-circuit protection. Determine the switch’s actual cut-in/cutout differential and air-unloader arrangement if present, rather than assuming all LF12 codes include the same mechanism. Qualified wiring is essential before connecting a three-phase motor.