Best Single-Phase Overload Relays for Motor Protection
Choosing the right single-phase overload relay is essential for protecting motors in HVAC, pumps, and general machinery. This guide highlights five reliable options from top brands, covering adjustable trip ranges, class 10 sensitivity, and ease of integration with TeSys D and similar contactor systems. Each entry includes a quick overview, key features, and practical considerations to help you select the best fit for your application.
| Product | Brand | Core Feature | Typical Use |
|---|---|---|---|
| LRD07 1.6/2.5A Overload Relay | Square D | Single-phase sensitivity, Class 10 | TeSys D compatible motor protection |
| LRD04 Relay | Telemecanique | Single-phase sensitivity, Class 10 | With TeSys D contactors |
| DPER07 Easy TeSys Thermal Overload | Schneider Electric | Reset options, compact modular design | 3-phase motor protection for HVAC and more |
| NR2-36 Electric Thermal Overload Relay | Walfront | 23-32A protection, motor protection | Broad 50-60Hz circuits |
| SSR-60AA Solid State Relay | MAKERELE | 60A, solid-state, contactless protection | Overload protection in single-phase circuits |
Square D LRD07 Overload Relay — 1.6/2.5A
The Square D LRD07 overload relay operates with TeSys D contactors, offering Class 10 single-phase sensitivity with a defined trip range of 1.6A to 2.5A. This device provides reliable protection against overcurrent conditions that could harm motor windings and drive systems. Its compact form suits space-constrained control panels, and its compatibility with standard TeSys D infrastructure simplifies retrofits and expansions.
Telemecanique LRD04 Overload Relay — Class 10
The Telemecanique LRD04 relay provides TeSys D compatibility with Class 10 single-phase sensitivity and a trip range suitable for common motor protection needs. This unit is designed for straightforward integration with existing contactor assemblies and supports dependable performance in HVAC, pumps, and machinery applications where precise overload detection is required.
Schneider Electric DPER07 Easy TeSys Thermal Overload Relay
The Schneider Electric DPER07 offers an Easy TeSys thermal overload solution with manual/automatic reset options and screw clamp terminals. It supports 1.6–2.5A trip ranges and is suitable for protecting motors in HVAC systems, pumps, compressors, and similar equipment. Its compact modular design helps maximize panel space while delivering robust overload protection and straightforward configuration for specific applications.
Antrader Thermal Overload Relay — 23-32A
The Antrader thermal overload relay covers higher current applications, rated in the 23–32A range. It offers reliable protection for motors where higher load demands are present. This unit is designed for straightforward installation and can be incorporated into various single-phase motor drives to guard against overload conditions and protect equipment from damage due to sustained overcurrent.
Buying Guide
Key considerations help determine the right single-phase overload relay for your system:
- Current range and sensitivity: Choose a relay with a trip range that matches your motor’s rated current and startup inrush. Class 10 sensitivity is common for many small to mid-size motors.
- Contactor compatibility: Many relays are designed to pair with TeSys D or similar contactors. Ensure mechanical and electrical compatibility with your existing control panels.
- Reset behavior: Manual vs automatic reset impacts startup sequence and downtime. Manual reset provides deliberate fault handling, while automatic reset minimizes downtime in some environments.
- Thermal vs solid-state protection: Thermal relays protect based on temperature rise, while solid-state relays provide electronic switching with fast trip responses. Your choice depends on environment, noise, and maintenance preferences.
- Environment and enclosure: Consider dust, moisture, and vibration. Look for compact, rugged designs that fit confined spaces without compromising protection standards.
- Voltage and insulation ratings: Check insulation ratings (e.g., 600V cUL or 690V IEC) to match system voltage and safety requirements.
- Maintenance and diagnostics: Some relays offer diagnostic features or status indicators that simplify maintenance and fault tracing.
When evaluating options, compare not only price but also long-term reliability, ease of installation, and compatibility with your motor protection strategy. For HVAC, pumps, and compressor systems, selecting a relay with proven thermal performance and a robust reset mechanism can reduce downtime and improve safety.