Overview
The Square D B6.9 overload relay heater (also designated B6.90) is a Type B thermal overload heater element engineered for reliable motor protection in industrial automation systems. This unit uses melting alloy sensing technology to detect overload conditions and trip the associated motor starter, preventing equipment damage from sustained overcurrent. The heater integrates seamlessly with Square D thermal overload relays and magnetic motor starters across a wide range of applications.
Key Features
- Type B thermal overload heater element with melting alloy sensing mechanism
- Rated for 4.55–6.9 amps full load amperage (FLA)
- Plug-in mounting design for quick installation and replacement
- Standard Trip characteristics for reliable motor protection
- Compatible with thermal overload relays and magnetic motor starters
- Compact form factor suitable for space-constrained control panels
Technical Specifications
- Heater Type: Type B thermal element
- Amperage Rating: 4.55–6.9 amps (nominal)
- Sensing Method: Melting alloy
- Trip Class: Standard Trip
- Mounting Style: Plug-in
- Manufacturer: Square D (Schneider Electric)
- Product Series: B Series thermal heater elements
- Condition: Used, tested
Typical Applications
The Square D B6.9 heater is widely deployed in:
- AC induction motor protection circuits
- NEMA-rated motor starters and contactors
- Industrial machinery with 4–7 amp motor loads
- Pump, compressor, and conveyor drive systems
- Manufacturing automation and process control equipment
Compatibility & Replacements
Compatible With
- Square D thermal overload relays (Class 10, Class 20, Class 30)
- Square D magnetic motor starters (Nema Size 00–2)
- Square D Class 8736 and 8910 series contactors
- Standard NEMA motor starter control circuits
- AC motor loads rated 4.5–6.9 amps
Replaces / Drop-In Replacement For
- Square D B6.90 (equivalent designation)
- Earlier generation Square D Type B heater elements with matching amperage rating
- Field replacement for worn or tripped heater units in existing installations
Works With
- Square D TeSys thermal overload relay line
- Square D PowerPact and CompactLogix automation platforms
- Standard IEC and NEMA control architectures
- Hardwired motor protection circuits (non-programmable)
- Manual and automatic motor starter control schemes
