Description
Phoenix Contact PLC-BSC-24DC21 | Relay Base, New Surplus
Architect’s Product Breakdown
The Phoenix Contact PLC-BSC-24DC21 (Part Number 2966016) serves as an ultra-slim 6.2mm interface terminal base designed to bridge field I/O devices with PLC input/output cards. Accommodating plug-in miniature relays (such as the REL-MR-24DC/21 series) or solid-state optocouplers, this modular socket integrates input conditioning logic—including an LED status indicator, freewheeling damping diode, and polarity protection—directly onto the DIN rail base.
Integrating the PLC-BSC-24DC21 into tight enclosure space allows engineers to maximize terminal density while utilizing plug-in bridging jumpers (such as FBST series) across adjacent sockets for supply voltage distribution. The screw-connection system supports wire gauges from 26 to 14 AWG with a solid torque retention design. Replacing failed switching elements takes seconds via the integrated engagement lever, preventing wire disconnection risks during hot-swap field servicing.
PLC-BSC-24DC21
Key Technical Specifications
- Manufacturer Part Number: 2966016
- Model Designation: PLC-BSC-24DC/21
- Nominal Input Voltage (U_N): 24V DC
- Protective Circuitry: Polarity protection diode, freewheeling/damping diode
- Status Display: Green LED input status indicator
- Connection Technology: M3 Screw Connection (0.14 mm² to 2.5 mm² / 26 to 14 AWG)
- Housing Width: 6.2 mm ultra-compact footprint
- Mounting Type: DIN rail NS 35/7,5 or NS 35/15
- Operating Temperature Range: -40°C to +60°C
- Flammability Rating: UL 94 V0 self-extinguishing housing
Field Engineer’s Pitfall Guide (Unique Value)
- Warning: Confusing the Relay Base Voltage with Relay Coil Rating. The internal freewheeling and protective circuit of the PLC-BSC-24DC21 drops voltage slightly. Inserting a standard off-the-shelf relay without matching Phoenix Contact’s specific REL-MR series pin configuration and coil tolerances will lead to chatter or failure to pick up.
- Warning: Overtightening Screw Terminals. The M3 clamping cage on these 6.2mm bases requires a strict torque setting between 0.6 Nm and 0.8 Nm. I have seen technicians strip the internal thread or snap the PCB trace solder joints by over-torquing with hand screwdrivers.
- Warning: Overlooking Continuous Current Limits on Bridging Comb Strips. When jumping 24V DC across 20+ adjacent PLC-BSC-24DC21 bases using plug-in bridge bars, ensure total current through the primary feed line does not exceed the comb strip’s max rating (32A max).
QA & Testing SOP (Transparency)
- Visual & Mechanical Check: Inspection of housing rails, terminal cage screws, locking/ejection lever, and OEM labeling.
- Circuitry & LED Continuity: Applied 24V DC to A1/A2 terminals to verify green LED illumination and polarity diode function.
- Relay Pin Socket Contact Test: Inserted test relay module to check socket retention force and pin-to-terminal continuity across changeover contacts 11, 12, and 14.
- Insulation Resistance Check: High-pot verification between input coil terminals and output contact side.
- ESD Packaging: Packaged in anti-static protective bags prior to shipping.
Technical FAQ
- Does the PLC-BSC-24DC21 include the relay module when ordered? No. This part number (2966016) is the basic terminal socket block only. Plug-in electromechanical relays (e.g., REL-MR-24DC/21) or solid-state relays must be ordered separately.
- Can I replace the relay without disconnecting the field wiring from the base? Yes. The integrated ejection lever releases the plug-in relay directly from the PLC-BSC-24DC21 socket without disturbing terminal screw connections.
- What is the difference between PLC-BSC-24DC/21 and PLC-BSC-24DC/21-21? The PLC-BSC-24DC/21 is a 6.2mm wide base designed for 1 changeover (SPDT) relay, while the /21-21 variant is a 14mm wide base designed for 2 changeover (DPDT) relays.
- Can I mount these terminal blocks side-by-side without spacing? Yes. The PLC-BSC-24DC21 is engineered for zero-gap side-by-side mounting on standard 35mm DIN rails.
