Eaton AA43P – NEMA A200 Thermal Overload Relay | 3-Pole | 19–135A | Panel Mount | Class 20
Eaton AA43P – NEMA A200 Thermal Overload Relay | 3-Pole | 19–135A | Panel Mount | Class 20
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The Eaton AA43P is a NEMA Size 4 thermal overload relay engineered for robust motor protection in high-current industrial applications. With a full-load amp range of 19 to 135 amps and Class 20 trip characteristics, this ambient-compensated, three-pole relay is designed for panel mounting on A200 NEMA starter assemblies. It safeguards motors against overload, phase unbalance, and single-phasing conditions — delivering reliable, maintenance-friendly protection across heavy-duty environments.
What Is a Thermal Overload Relay?
A thermal overload relay protects motors by monitoring current and interrupting the control circuit when sustained overcurrent is detected. It uses bimetallic thermal heater elements: as motor current exceeds safe levels, heat causes the bimetal to deflect, tripping the relay and opening the motor circuit. This prevents winding damage and motor burnout. The AA43P’s ambient compensation feature adjusts the trip point based on surrounding temperature, making it accurate in both hot and cold environments.
Key Specifications
- Part Number: AA43P
- Manufacturer: Eaton (Cutler-Hammer)
- Series: A200 / Freedom NEMA
- NEMA Size: 4
- Poles: 3-Pole
- Full Load Amp Range: 19 – 135A
- Trip Class: Class 20
- Type: Thermal Type A
- Auxiliary Contact: 1 Normally Closed (1NC)
- Ambient Compensation: Yes (Compensated)
- Mounting: Panel mounted
- Reset: Manual or Automatic
- Compatible With: Eaton A200 NEMA motor starters
Applications
- Large three-phase motor protection (pumps, compressors, fans)
- Industrial motor control centers (MCCs)
- HVAC and refrigeration equipment
- Conveyor systems and material handling
- Manufacturing automation and process control
- Water and wastewater treatment systems
AA43P vs AA43A – Mounting Difference
The AA43P is panel mounted, making it suitable for standalone installations where the relay is mounted directly to a panel or enclosure surface. The AA43A is starter mounted and installs directly onto the A200 contactor body. Both share the same 19–135A full-load range and Class 20 trip characteristics.
Why Choose Eaton Freedom NEMA Overload Relays?
Eaton’s A200 Freedom NEMA overload relays feature adjustable bimetallic ambient-compensated protection, interchangeable heater packs, and screw-type power terminals with captive, backed-out self-lifting pressure plates — significantly reducing installation and maintenance time. Available in sizes covering applications up to 900 HP, these relays minimize inventory complexity while maximizing coverage.