Schneider Electric LRD07 — Thermal Overload Relay Selection Guide

By Abdullah Zahid
12 min read
Schneider Electric LRD07 TeSys Deca thermal overload relay direct-mount on LC1D contactor for three-phase motor starter

Schneider Electric LRD07 TeSys Deca Thermal Overload Relay — Complete Specifications, Pricing and Selection Guide

If you are specifying or replacing a thermal overload relay for a compact three-phase motor starter and your contactor is a TeSys D-series LC1D, the Schneider Electric LRD07 is the relay most likely on your shortlist. Covering an adjustable range of 1.6 to 2.5 A with Class 10 trip characteristics, direct-mount architecture, and built-in phase-loss sensitivity, this relay handles the protection needs of small motors in the 0.5 to 0.75 kW range without additional wiring, programming, or external components. The one decision that determines whether this is the right part: confirm that your motor's full-load amperage falls within 1.6 to 2.5 A before you order anything else.

If you have already confirmed the LRD07 is the correct relay for your application, check current pricing and availability at LeadTime.ca — ships worldwide.

Who Should Buy the LRD07 — and Who Shouldn't

The Schneider Electric LRD07 is the right choice for engineers and technicians whose motor starter meets all of the following criteria:

  • Motor nameplate full-load amperage (FLA) falls within 1.6 to 2.5 A — this is the relay's fixed adjustable window and cannot be extended
  • The contactor in the starter assembly is an LC1D09, LC1D12, LC1D18, LC1D25, LC1D32, or LC1D38 TeSys D-series unit — direct-mount requires this exact family
  • Circuit voltage is 690 V AC (or 600 V AC per UL 508) — the LRD07 is not rated for 208 V, 240 V, 480 V, or DC applications
  • Class 10 trip response is acceptable — the relay trips in 10 seconds or less at 2 times rated current per IEC 60947-4-1
  • Phase-loss detection is required or acceptable — it is included as standard and cannot be disabled
  • Reset mode flexibility is needed — the LRD07 offers user-selectable manual or automatic reset via a dial without rewiring

If your motor FLA exceeds 2.5 A, the LRD08 (2.5 to 4 A) is the correct next step. If you are not using a TeSys D-series contactor, a standalone relay from the LRB family is the appropriate alternative. If Class 20 trip time is required for your application, the LRD07 is not the right model — consult the LRD series Class 20 variants.

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What the LRD07 Actually Does in a Motor Starter Assembly

The Schneider Electric LRD07 is a three-pole bimetallic thermal overload relay that mounts directly underneath TeSys D-series contactors in a motor starter assembly. Its role is straightforward: when sustained motor current exceeds the relay's dial-set threshold, the bimetallic strip heats, deflects, and opens the contactor's control circuit — de-energizing the motor before winding damage occurs. This is fundamentally different from a circuit breaker, which protects against short circuits. The LRD07 protects the motor from sustained overloads, single-phase loss, and current imbalance — conditions that a breaker would not catch before the motor overheats.

The relay's adjustable range runs from 1.6 to 2.5 A, set by a dial on the relay face that the technician aligns to the motor's nameplate FLA. Class 10 trip characteristics mean the relay responds in 10 seconds or less at twice the rated current — fast enough to prevent thermal damage in most three-phase motor applications while tolerating normal inrush during starting. Ambient temperature compensation, rated across -30°C to +60°C, automatically adjusts the trip threshold to prevent false trips in cold environments or sluggish response in heat — a real-world advantage in outdoor enclosures, cold storage facilities, and process environments with variable ambient conditions.

Phase-loss sensitivity is integrated and active at all times. The relay trips when two of the three phases carry 130% of the relay's set current — a reliable indicator of a lost phase on the utility side or at the motor terminals. This protection is included at no added cost and requires no wiring modification or configuration, which represents a genuine value advantage for three-phase motor circuits where phase loss is a realistic fault scenario.

Typical System Architecture for a TeSys D Motor Starter

The LRD07 sits at the load-side interface between the contactor and the motor — the last active protection device before power reaches the motor windings. Understanding where it fits in the control chain helps confirm whether it belongs in your design.

  • Upstream: main disconnect or motor circuit protector provides short-circuit protection and isolation
  • Contactor (LC1D09 through LC1D38): controls motor energization and de-energization on command from the control circuit
  • LRD07 (direct-mounted under contactor): provides continuous current monitoring, trips the contactor control circuit on overload, phase loss, or phase imbalance
  • Auxiliary contacts (1NO–1NC): feed trip status signals to a PLC input, alarm relay, or indicator lamp for fault annunciation
  • Downstream: motor winding terminals receive protected three-phase power only when both the contactor and relay allow it

Where the LRD07 Gets Used and Why

Food and beverage facilities represent one of the most common deployment environments for the LRD07. Conveyor belt drives, small mixer motors, and pump starters in washdown-adjacent areas operate in the 0.5 to 0.75 kW range where 1.6 to 2.5 A motor FLA is typical. The direct-mount design keeps starter assemblies compact — important when panel space is limited on production equipment.

HVAC applications use the LRD07 in fan motor starters where motors in the small horsepower range require reliable overload protection without the complexity of electronic relays. Phase-loss detection is particularly valuable here because a single lost phase on a fan motor can go undetected by a standard circuit breaker for long enough to cause winding failure.

Water and wastewater treatment installations rely on the LRD07 for small pump protection. Pump starters in lift stations, chemical dosing systems, and aeration blowers frequently use TeSys D contactors as standard hardware, making the LRD07 a natural fit for the protection stage. The ambient compensation range — extending down to -30°C — handles outdoor pump station environments without nuisance tripping in winter conditions.

Maintenance technicians replacing failed relays in existing motor starters represent a significant portion of LRD07 purchases. Because the mounting footprint and terminal type are identical to the part being replaced, the swap restores protection without rewiring the enclosure — an important advantage when the priority is minimizing downtime on a production line.

Application Typical Deployment
Food and beverage conveyor or mixer Compact TeSys D starter on a 0.5–0.75 kW motor; LRD07 direct-mounted for phase-loss and overload protection
HVAC fan motor starter LC1D contactor plus LRD07 in MCC section; phase-loss protection guards against utility imbalance faults
Water/wastewater pump station Outdoor or unheated enclosure; ambient compensation from -30°C to +60°C prevents nuisance trips
Thermal relay replacement (like-for-like) Direct swap on existing LC1D09–LC1D38 starter; no rewiring required, restores full protection
OEM pre-assembled motor starter Panel builder integrates LRD07 as standard BOM item for compact starter modules shipped to end users
Cold storage facility motor protection -30°C ambient-compensated relay prevents false trips in cold warehouse pump and fan starters

LRD07 Specifications: What Engineers Need to Confirm Before Ordering

Specification Value
Amperage Range 1.6 to 2.5 A (adjustable via dial to motor FLA)
Trip Class Class 10 — trips in 10 seconds or less at 2× rated current per IEC 60947-4-1
Voltage Rating 690 V AC (0–400 Hz); 600 V AC per UL 508. Not rated for DC.
Poles 3 — three-phase motor protection only
Reset Type Manual or Automatic — user-selectable via dial, no rewiring required
Phase-Loss Sensitivity Included as standard — trips at 130% of Ir on two phases; cannot be disabled
Ambient Operating Range -30°C to +60°C — ambient-compensated thermal characteristic
Contactor Compatibility Direct mount on LC1D09, LC1D12, LC1D18, LC1D25, LC1D32, LC1D38 TeSys D-series only
Dimensions (W × D × H) Approximately 45 mm × 70 mm × 70 mm
Certifications UL 508, CSA C22-2 No. 14, EN/IEC 60947-4-1, ATEX 94/9/CE, RoHS

Full technical specifications are available on the product page at LeadTime.ca.

LRD07 vs. LRD08 vs. LRB vs. Solid-State: Which Relay Do You Actually Need?

Feature LRD07 LRD08 LRB (Standalone) Solid-State Relay
Amperage Range 1.6–2.5 A 2.5–4 A Various 0.5–40 A (varies by model)
Trip Class Class 10 Class 10 or Class 20 Class 10 or 20 Adjustable (Class 10–30)
Mounting Direct on LC1D09–LC1D38 Direct on LC1D25–LC1D63 Standalone — rail or base Standalone — rail or base
Phase-Loss Detection Yes — included standard Yes — included standard Optional depending on model Integrated (typically)
Ambient Compensation Yes — -30°C to +60°C Yes Yes (model-dependent) Yes (electronic)
Wiring Complexity Minimal — direct mount Minimal — direct mount Moderate — separate terminals Low — pre-wired typically
Programming Required No No No Yes — electronic controller
Typical Application Compact starters 0.5–0.75 kW Medium starters 1–2 kW Retrofit or flexible mounting High-precision programmable protection

If your motor's full-load amperage exceeds 2.5 A, the LRD07 will not provide adequate protection — the LRD08 or a higher-range relay is the correct choice. If you are not working with a TeSys D-series contactor, the LRB standalone family is the appropriate alternative. Check current availability of the LRD07 at LeadTime.ca and use the contact page if you need help confirming which model fits your starter.

Expert Verdict: Is the LRD07 Worth Specifying?

The Schneider Electric LRD07 earns a clear recommendation for panel builders and maintenance teams who are already standardized on TeSys D contactors and are protecting motors with a nameplate FLA between 1.6 and 2.5 A. The direct-mount architecture eliminates a separate relay, reduces terminal connections, and cuts assembly time on compact three-phase motor starters — real advantages when building multiple starter units or replacing relays under production pressure. Phase-loss detection is included at no premium, and the -30°C to +60°C ambient-compensated thermal characteristic means the relay behaves predictably across the full range of environments where small industrial motors operate. For a maintenance technician replacing a failed relay in an existing starter, the like-for-like mounting makes this an immediate swap with no wiring changes. For an OEM embedding motor protection in a pre-assembled starter destined for food and beverage, HVAC, or water treatment applications, the LRD07 is a proven, certifiable choice backed by UL 508, CSA C22-2 No. 14, and IEC 60947-4-1 compliance.

The LRD07 has real limits that are worth stating plainly. If the motor FLA exceeds 2.5 A, this relay will not adequately protect the motor — the LRD08 covers 2.5 to 4 A and is the direct next step. If your contactor is an LC1E, LC2, or any series other than the LC1D09 through LC1D38 range, the LRD07 will not mount mechanically, and a standalone relay is necessary. If your application requires Class 20 trip time — for circuits that tolerate longer overload durations, such as those preceding soft-starters or VFDs — the LRD07's Class 10 characteristic is not suitable, and the Class 20 variants in the LRD series are the correct specification. Single-phase and DC circuits are outside this relay's ratings entirely.

From a procurement standpoint, the LRD07 is a standard commodity item stocked by major industrial distributors, with typical lead times of same-day to next business day for in-stock orders. Buying through a specialist industrial distributor rather than a general marketplace seller matters here not because of price, but because of compatibility verification — the most common and costly mistake with this relay is ordering the wrong amperage range or the wrong model for the contactor in the starter. A specialist distributor can confirm compatibility before the order ships, which is worth considerably more than a few dollars saved at checkout. View current pricing and stock status for the LRD07 at LeadTime.ca — available for order worldwide.

For volume pricing on multiple units or to confirm lead time before committing to a build schedule, contact the LeadTime.ca team directly — we ship worldwide.

What Engineers Need to Know Before Ordering the LRD07

Community discussion specific to the LRD07 is limited across the major industrial automation forums — no significant threads were located on Reddit, PLCTalk, PLCS.net, or MrPLC for this model. That absence reflects the relay's nature as a commodity component: when it is specified and installed correctly, it simply works, and technicians have little reason to post about it. What that also means is that the questions buyers most need answered tend to surface at the point of order, not after installation — which is exactly why getting the specification right before purchasing matters more than it might for a more complex device.

The most consistent source of ordering errors for relays in this category is amperage range confusion. The LRD07 and LRD08 are stocked side by side, cover overlapping current regions at their boundary (both include 2.5 A at the edge of their respective ranges), and share identical mounting architecture. Ordering based on part number alone without verifying the motor nameplate FLA against the relay's adjustment window is the single most common pre-purchase mistake — and it results in either a relay that nuisance-trips during normal starting (undersize) or one that fails to protect the motor during an overload (oversize). Neither outcome is acceptable in a production environment. The fix is simple: read the motor nameplate, record the FLA, and confirm it falls between 1.6 and 2.5 A before the order is placed.

The second area where specialist advice adds clear value is contactor compatibility. Technicians retrofitting or replacing relays in older starters sometimes encounter contactors with worn or obscured model markings, or they assume that any Schneider relay will fit any Schneider contactor. The LRD07 mounts only on LC1D09, LC1D12, LC1D18, LC1D25, LC1D32, and LC1D38 contactors. An LC1E, LC2, or any other series will not accept this relay mechanically. If the contactor model cannot be confirmed from the nameplate, the correct action is to consult the starter's documentation or contact a specialist distributor before ordering — not to attempt a physical fit test with the relay in hand. LeadTime.ca's team can assist with compatibility verification before your order ships, which eliminates the commissioning delays that result from receiving the wrong part on a tight schedule.

Wiring and Installation Overview

The following points summarize the key requirements for installing and wiring the LRD07. For complete wiring diagrams and control circuit schematics, refer to the official Schneider Electric installation documentation supplied with the relay.

  • Before mounting, confirm the contactor model is within the LC1D09–LC1D38 range and that the motor nameplate FLA falls between 1.6 and 2.5 A — these are the two checks that prevent the most common installation errors
  • The relay seats directly on the underside of the TeSys D contactor by aligning mounting tabs with the contactor's slots and pushing down firmly until fully seated; the relay should not rock or shift when properly engaged
  • Power circuit terminals accept 1 to 6 mm² solid or 1 to 4 mm² flexible cable; control circuit (auxiliary) terminals accept 1 to 2.5 mm² solid or flexible; all terminals tighten to 1.7 N·m — use a torque wrench or calibrated hand tightness and do not over-tighten
  • After wiring, set the adjustment dial to the motor's exact FLA from the nameplate — not an estimated or rounded value; document the setting in the starter schematic for future reference
  • Verify reset mode selection (manual or automatic via dial) matches the control logic before energizing; in manual reset mode the motor will not restart after a trip until an operator physically resets the relay

Wrong-Part Prevention Checklist

Before placing your order for the Schneider Electric LRD07, work through each of the following items. This checklist is drawn directly from the most common specification and ordering errors associated with this relay family.

  1. Confirm motor nameplate FLA falls within 1.6–2.5 A. Do NOT assume; oversize relay will not protect the motor; undersize relay will trip on inrush current during normal starts.
  2. Verify the contactor in your starter is an LC1D series (TeSys D); if it is LC1E, LC1F, LC2, or another series, the LRD07 will not mount directly.
  3. Check the specific contactor model (LC1D09, LC1D12, etc.) in your starter. LRD07 fits LC1D09–LC1D38; confirm the contactor is within this range.
  4. Confirm circuit voltage is 600–690 V AC. LRD07 is not rated for 208 V, 240 V, 480 V, or DC.
  5. Verify you need or want phase-loss detection. If your circuit lacks three-phase power or does not require this protection,

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