Overview
The Square D 9999-SX-6 /B electrical interlock is a Class 9999 auxiliary contact assembly designed for Type S NEMA motor starters and contactors. Built for industrial control panels and motor circuit applications, this interlock provides reliable electromechanical switching with external field-convertible design. The Series B (revision /B) unit is rated NEMA A600 and supplies a single normally open (NO) contact for control interlocking and permissive logic circuits.
Key Features
- Class 9999 Type SX-6 auxiliary contact assembly
- NEMA A600 AC rating with 600 VAC pilot duty capability
- Single NO (normally open) contact, field-convertible design
- External mounting on Type S contactors and starters (NEMA sizes 00–7)
- Robust mechanical latch mechanism for dependable contact operation
- Used, tested condition—fully functional and ready to install
Technical Specifications
- Manufacturer: Square D (Schneider Electric)
- Part Number: 9999-SX-6 /B (9999SX6)
- Class/Type: Class 9999, Type SX-6, Series B
- Contact Configuration: 1 NO (normally open)
- AC Rating: NEMA A600
- Voltage (AC): 120–600 VAC
- Current (Pilot Duty): 6 A at 0–120 VAC
- Power Rating: 720 VA (pilot duty)
- Mounting: External, field-convertible
- Compatible Contactor/Starter Sizes: NEMA 00–7 (SA-SJ series)
- Condition: Used, tested, fully operational
Typical Applications
The 9999-SX-6 /B interlock is commonly used in:
- Multi-motor control circuits requiring interlocking or permissive logic
- Reversing or two-speed starter applications
- Safety circuits where auxiliary contacts signal motor contactor status
- Industrial machinery control panels and motor control centers (MCCs)
- HVAC and pump automation systems
- Maintenance and retrofit of existing Square D starter panels
Compatibility & Replacements
Compatible With
- Square D Type S NEMA motor starters and contactors (SA/SJ series)
- NEMA contactor sizes 00, 0, 1, 2, 3, 4, 5, 6, and 7
- Industrial control panels and motor control centers (MCCs)
- AC pilot duty circuits (120–600 VAC)
Replaces / Drop-In Replacement For
- Square D 9999-SX-6 (earlier revisions or OEM original equipment)
- Verify exact compatibility with your specific starter model before ordering
Works With
- Traditional hardwired relay logic and control circuits
- Square D Industrial Control System (ICS) platforms
- Auxiliary contact feedback for industrial PLCs and controllers
