ABB

Product Background

R&D Background

ABB developed the SYNPOL‑D system family for industrial process control, power‑plant and marine automation back in the 1990s. The CMA121 is the dedicated plug‑in switching‑mode power supply card for the SYNPOL‑D / Symphony DCS and Advant Controller racks. It adopts high‑frequency switching‑power topology, designed for harsh industrial environments. It supports redundant power configuration for high‑availability critical control systems.

Key hardware features: Wide‑range AC input (100‑240 VAC, 50/60 Hz), regulated 24 VDC output, 12.5 A; galvanic isolation between input and output; built‑in inrush‑current limiter; isolated fault‑alarm relay contact; fan‑less passive cooling.

Current Status: This hardware is End‑of‑Life (EOL), discontinued by ABB. No new original production. The market mainly supplies refurbished, repaired or used spare units, for maintenance and replacement of existing legacy DCS/control systems.

ABB SYNPOL‑D CMA121 Power Supply Card, Order‑No. 3DDE300401

Core Functions

Note: This is a system‑rack power supply card. It does NOT process control logic or collect field signals; it only provides stable DC power for the whole subrack.

1. Regulated DC power conversion Accepts wide‑range AC input, converts to stable filtered 24 VDC output for the subrack backplane. Supplies power to CPU boards, I/O modules and other cards inside the control rack. Output ripple is kept low for noise‑sensitive industrial electronics.
2. Built‑in circuit protection Over‑voltage, over‑current, short‑circuit protection; overload automatic recovery. Active inrush‑current limiter to avoid tripping upstream breakers when power‑on capacitive loads.
3. Redundancy‑ready design Supports parallel redundant operation. Two CMA121 cards can be installed in one subrack. Outputs can be connected with external blocking diodes or paired with CMA132 redundancy module to achieve hot‑standby power supply. Single‑card failure will not shut down the whole control system.
4. Fault alarm signal output Equipped with isolated change‑over relay alarm contact. When power‑supply fault occurs, it sends alarm signal to the control system for remote monitoring and fault reporting.
5. Status indication On‑board LED indicators show power‑on and fault status for on‑site maintenance troubleshooting.More products: www.plcva.com

Hardware Interfaces

• Backplane connector: Plug into dedicated power slot of SYNPOL‑D / Symphony subrack, supply 24 VDC to rack backplane
• AC power input terminals: Wide‑range AC input
• Isolated alarm relay output contact: For system fault notification
• Front‑panel screw locking for secure rack‑mount installation (Eurocard 3U format)

Main Applications & Deployment Sites

Core application: Rack‑mount power supply for ABB SYNPOL‑D, Symphony DCS and Advant Controller control systems, for critical industrial process control and power‑plant automation.

1. Thermal / Hydro Power Plants Supply power for DCS control racks in power‑plant control rooms, for boiler, turbine and generator process control systems.
2. Oil & Gas, Refineries & Chemical Plants Process control DCS systems, high‑availability redundant power configuration for critical process control racks.
3. Marine Automation (Shipboard Control Systems) Marine‑approved variant with DNV, ABS, LR marine certifications. Used for ship‑automation control racks on cargo ships, offshore vessels and marine power stations.
4. Industrial Captive Power Plants & Heavy‑industry factories Steel, paper‑making, cement, chemical plants, for legacy ABB Advant / Symphony DCS control cabinets.

Important distinction:

• CMA121: System rack power‑supply card, supplies power for all other boards in the control subrack.
• 216VC62a: Relay‑protection CPU board for generator fault protection.
• UNITROL 1020: Generator excitation AVR regulator. They are often deployed together in power‑plant control rooms, but have completely different functions.

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