ABB CMA 121 SYNPOL D Power Supply Card (3DDE300401)

General Description

The CMA 121 is a member of ABB's SYNPOL D family of power supply units designed for use in the Symphony DCS (Distributed Control System) and Advant controller series. It delivers clean, regulated DC power to the backplane and connected modules, featuring built-in protection against overcurrent, overvoltage, and short circuits. Its compact, Eurocard form factor allows easy installation in standard subracks.

Key Features

• Input Voltage Range: 100-240 V AC (50/60 Hz) or 110-340 V DC (wide range).

• Output Voltage: 24 V DC ±1%, regulated, with low ripple.

• Output Current: 5 A continuous (10 A peak for 10 seconds).

• Efficiency: > 88% at full load.

• Protections: Overload, overvoltage, overtemperature, and reverse polarity protection.

• Redundancy Ready: Can be paralleled with another CMA 121 for 1+1 redundancy using external diodes.

• Hot-Swappable: Designed for insertion/removal under power without disturbing system operation.

• Status Indication: LED indicators for input present, output OK, and fault.

Technical Specifications

• Operating Temperature: 0°C to +60°C (derating above 55°C).

• Storage Temperature: -40°C to +85°C.

• Humidity: 5% to 95% non-condensing.

• Isolation: Input to output 3 kV AC, input to ground 2 kV AC.

• Dimensions: 3U x 4HP (Eurocard, 100 x 160 mm front panel).

• Weight: 0.4 kg.

Functional Description

The CMA 121 uses a high-frequency switching topology for compactness and efficiency. It accepts a wide range AC or DC input, rectifies and filters it, then switches at high frequency to produce a regulated 24V output. The module includes an active inrush current limiter to prevent nuisance tripping when powering capacitive loads. An internal ORing FET allows seamless parallel operation for redundancy. The module also provides an isolated alarm contact (changeover relay) to signal failure to the system.

Applications

• Power supply for Symphony S+ series I/O racks.

• Advant Controller 410/450 backplane power.

• Field termination assemblies requiring 24V DC.

• Redundant power configurations in critical processes (power plants, refineries).

Installation and Maintenance

The card plugs into a dedicated power slot in the subrack. It is held in place by front panel screws. For redundant operation, two modules are installed and the outputs are connected via external blocking diodes or using a redundancy module like the CMA 132. Regular inspection involves checking LED status and ensuring adequate ventilation. No periodic maintenance is required.

Compliance

• CE, UL 508, CSA C22.2 No. 14.

• Marine type approvals (ABS, DNV, LR) available.

Note: This technical description is for reference. For exact specifications, refer to the ABB CMA 121 product manual.