Schneider Electric TeSys LR9F Electronic Overload Relay
Overview
The Schneider Electric LR9F electronic overload relay protects large three-phase motors driven by TeSys F contactors, covering thermal setting ranges from around 60 A up to 630 A across the LR9F family, well beyond the current handling of a standard bimetallic relay. Where the TeSys D range pairs with the mechanical LRD relay, the Schneider Electric LR9F is the equivalent protection device for TeSys F, giving large-motor starter panels electronic-grade protection accuracy and diagnostics at a current class where a purely mechanical solution becomes impractical.
As the official authorized partner and exclusive regional representative for Schneider Electric, Seven Star LLC proudly supplies the Schneider Electric LR9F range from stock in Muscat, backed by genuine factory warranty and technical support for engineering, procurement, and maintenance teams across Oman and the wider GCC. Every unit shipped is sourced through Schneider Electric’s authorized distribution channel, ensuring buyers receive correctly rated relays with full traceability rather than unverifiable grey-market stock for a device protecting expensive large-motor assets.
Operating Principle of the Schneider Electric LR9F Relay
Unlike the bimetallic LRD, the Schneider Electric LR9F uses current transformers on each phase to feed an electronic measurement and trip circuit, giving substantially more accurate and repeatable protection at high current levels than a purely thermal-mechanical design can achieve. The electronics continuously evaluate thermal overload, phase failure, phase unbalance, prolonged motor starting time, and stalled rotor conditions, tripping the associated contactor coil circuit through built-in 1 NO + 1 NC auxiliary contacts the moment any protected condition is detected, per IEC 60947-4 trip-time curves for class 10 or class 20 duty.
Because the trip decision is made electronically rather than by physical bimetal deflection, the Schneider Electric LR9F resets faster and more consistently after a trip event, and its thermal memory accounts for motor heating history more accurately when deciding whether an immediate restart is safe. A DC 24 V auxiliary supply powers the electronics independently of the load current being measured, keeping protection active and diagnostics available even during commissioning or low-load testing when the motor itself is not drawing full current.
Engineering Design of the Schneider Electric LR9F
The Schneider Electric LR9F mounts directly below its associated TeSys F contactor – for example LC1 F115, F150, or F185 – using a dedicated support mounting plate (LA7F901) that keeps the relay mechanically integrated with the starter assembly rather than requiring separate panel space. The front face carries a thermal adjustment dial, test, stop, and reset buttons, a trip indicator, and screw-clamp terminals for the 1 NO + 1 NC trip signaling contacts, keeping all operator interaction points accessible without opening the unit.
Rated phase-to-phase voltage up to 1000 V AC on the measurement inputs and a 24 V DC electronics supply give the Schneider Electric LR9F the headroom to serve high-voltage industrial motor circuits reliably. The relay is multi-standard certified across IEC, UL, CSA, CCC, and marine approvals, and Green Premium RoHS/REACH compliant, matching the certification profile expected on large infrastructure and petrochemical projects across the GCC.
Key Features
The Schneider Electric LR9F brings electronic-grade accuracy to large-motor overload protection, and its feature set reflects that duty:
- Covers thermal setting ranges from approximately 60 A up to 630 A across the LR9F family, matching TeSys F contactor current classes.
- Selectable class 10 or class 20 tripping curves per IEC 60947-4 to match motor starting characteristics.
- Current-transformer-based electronic measurement delivers greater trip accuracy than bimetallic relays at high current.
- Protects against overload, phase failure, phase unbalance, prolonged starting, and stalled rotor conditions.
- Mounts directly below TeSys F contactors on a dedicated support plate for a fully integrated starter assembly.
- Built-in 1 NO + 1 NC trip signaling contacts report fault status to the control and alarm system.
- 24 V DC auxiliary supply keeps protection electronics active independent of motor load current.
- Multi-standard certified across IEC, UL, CSA, CCC, and marine approvals for cross-market projects.
Industrial Applications
The Schneider Electric LR9F protects the large motors most exposed to costly failure across Oman and the GCC: high-capacity RO desalination and seawater intake pumps, district cooling plant compressors, and heavy conveyor or crusher drives in industrial facilities around Muscat, where an undetected overload can mean a multi-week motor rewind and lost production. Its class 10/20 selectable curves also make it suitable for motors with longer, higher-inertia starting profiles that a fixed-class relay would trip prematurely.
As the officially authorized partner for Schneider Electric, Seven Star LLC distributes the LR9F range to EPC contractors and panel integrators building large motor control centers for petrochemical, metals, and power generation facilities in the Sohar and Salalah economic zones, where protecting six and seven-figure motor assets justifies the added diagnostic capability of electronic overload protection. The relay is equally specified in utility-scale water and wastewater treatment plants across the Sultanate, wherever motor size pushes past the practical limit of a mechanical thermal relay.
Technical Specifications
The table below summarizes the core parameters of the Schneider Electric LR9F electronic overload relay range.
| Parameter | Specification |
|---|---|
| Model | LR9F range (e.g. LR9F5367, LR9F5571, LR9F7579) |
| Thermal Setting Range | Approx. 60 A to 630 A (model dependent) |
| Tripping Class | Class 10 or Class 20, selectable |
| Rated Voltage (Phase-Phase) | Up to 1000 V AC |
| Auxiliary Supply | 24 V DC |
| Auxiliary Contacts | 1 NO + 1 NC trip signaling contacts |
| Protection Type | Overload, phase failure, unbalance, stalled rotor, prolonged start |
| Mounting | Direct mount below TeSys F contactor via LA7F901 support plate |
| Compatible Contactors | TeSys F LC1F range (e.g. LC1 F115, F150, F185) |
| Standards | IEC, UL, CSA, CCC, Marine |
| Environmental Compliance | Green Premium, RoHS/REACH |
Request a Quote for Schneider Electric TeSys LR9F Electronic Overload Relay
Panel builders and plant engineers in Oman and the GCC can request a formal RFQ for the Schneider Electric LR9F electronic overload relay from Seven Star LLC, with regional warehouse stock in Muscat and full technical datasheets available on request. As the authorized partner for Schneider Electric in Oman and the GCC, our instrumentation and automation division supports correct thermal sizing and large-motor starter configuration for every LR9F order – contact Seven Star LLC today to confirm availability and lead time.
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