Overview
The Phoenix Contact PLC-BSC-24DC/21-21 is a compact relay base terminal block designed for modular PLC and automation systems. This 14 mm terminal block mounts directly on standard DIN rail NS 35/7.5 and provides 2 changeover (PDT) contacts with 24V DC nominal input voltage. As a base-only unit without integrated relay, it accepts plug-in miniature relays like the REL-MR-24DC/21-21AU, allowing flexibility in system configuration and cost-effective modularity.
Key Features
- 2 changeover contacts (PDT – pole double throw) for flexible switching control
- 24V DC nominal input voltage with integrated polarity and damping diode protection
- Screw connection terminals support conductor cross section 0.14–2.5 mm² rigid or flexible
- LED status display for visual input signal confirmation
- 100% operating factor – rated for continuous duty operation
- Base-terminal-block design accepts plug-in relay modules for system modularity
- Gray housing (RAL 7042) with UL/cUL recognition and EAC certification
Technical Specifications
The PLC-BSC-24DC/21-21 meets industrial automation standards for relay-based control circuits in compact DIN rail panels. Screw terminal connection ensures secure, field-serviceable wiring without special tools.
Typical Applications
- Industrial control panels requiring modular relay logic
- Machine automation and process control systems
- HVAC and building management systems
- Safety circuit interfacing where plug-in relay flexibility is needed
- DIN rail enclosure installations with space constraints
Compatibility & Replacements
Compatible With
- DIN rail NS 35/7.5 standard mounting
- Phoenix Contact REL-MR miniature relay series (24DC/21-21, 24DC/21-21AU)
- Phoenix Contact FBST terminal block accessories for potential bridging
- PLC control systems and safety relay circuits rated 24V DC
- Standard industrial automation enclosures with DIN rail infrastructure
Replaces / Drop-In Replacement For
- Equivalent 14 mm, 2-contact relay base units with 24V DC rating
- Legacy Phoenix Contact relay bases (verify physical dimensions and contact arrangement before substitution)
Works With
- Phoenix Contact ProfiNet and EtherNet/IP gateway modules
- Allen-Bradley CompactLogix/ControlLogix PLC systems with 24V DC control power
- Siemens S7-1200/1500 automation systems in 24V DC environments
- Any 24V DC relay-logic or hybrid control architecture
