Selecting the ABB CMA126 is the first step; correct installation and configuration are crucial for reliable operation. This guide provides a practical, step-by-step overview for panel builders, electricians, and technicians, covering the key considerations for selecting the right variant, wiring the module, and integrating it into a motor control circuit.
Pre-Installation: Selection and Compatibility Check
Warning: All installation and wiring must be performed by a qualified electrician in accordance with local electrical codes. Ensure all power is disconnected before starting work.
Step 1: Verify Compatibility
The CMA126 is designed for specific ABB contactors and overload relays. Before procurement, confirm:
- Contactor Series: Check that the module is compatible with your contactor (e.g., ABB ESB series contactors).
- Rated Current: Ensure the module is suitable for the current rating of your motor starter combination.
- Reference the Datasheet: Always consult the official ABB CMA126 datasheet for a list of compatible components. Using an incompatible module can lead to improper operation or damage.
Step 2: Determine Required Features
- Undervoltage Release: Decide if your application requires the undervoltage release option for anti-restart protection.
- Auxiliary Contacts: The standard module typically provides one NO and one NC contact. Verify this meets your signaling needs.
Step-by-Step Installation and Wiring
Step 1: Physical Mounting
- De-energize: Ensure the main power supply to the motor starter circuit is locked out and tagged out (LOTO).
- Mount on DIN Rail: The CMA126 module is designed to snap onto a standard 35mm DIN rail. Mount it directly adjacent to the contactor and overload relay for a neat and compact assembly.
- Mechanical Connection: Some modules may have a mechanical link or lever that connects to the contactor. Ensure this is engaged if required, as it may be used for manual operation or status indication.
Step 2: Electrical Wiring
Refer to the wiring diagram printed on the side of the module or provided in its documentation.
- Power Supply Connections: Connect the control voltage (e.g., 24V DC or 110V AC) to the designated terminals (often labeled A1/A2). Observe the correct polarity for DC supplies.
- Control Command Inputs: Connect your start/stop command devices. This is typically done by wiring:
- A maintained or momentary "Start" signal to the appropriate terminal.
- A "Stop" signal (often a normally closed contact from a push button or a PLC output) to its terminal.
- Contactor Coil Connection: Connect the output of the CMA126 module to the coil terminals (A1/A2) of the contactor. The module acts as the switch that energizes the contactor.
- Overload Relay Connection: Connect the output signals from the overload relay (typically the NC - Normally Closed - contact of the trip relay) to the designated "trip" input on the CMA126. This allows the module to receive the overload signal.
- Auxiliary Contact Wiring: Wire the module's auxiliary NO and NC contacts to your PLC's digital inputs or to pilot lamps on the panel door to provide remote status indication.
Step 3: Configuration and Commissioning
The CMA126 is configured via hardware wiring and simple selectors, not software.
- Control Mode Selection: The module may have a small selector switch or jumper to set the control mode (e.g., momentary pulse or maintained command). Set this according to your control system's design.
- Voltage Check: Double-check that the control voltage matches the module's rating.
- Visual Inspection: Verify all connections are tight and correct.
Step 4: Testing and Operation
- Apply Control Power: Re-apply the control voltage first (keep the main power to the motor disconnected).
- Test Control Logic:
- Press the "Start" button. You should hear the contactor pull in with a distinct "clunk." The "ON" LED on the CMA126 should illuminate.
- Press the "Stop" button. The contactor should drop out, and the "ON" LED should turn off.
- Test Function: Press the TEST button on the module. The contactor should pull in, and the "ON" LED should light, but the main power circuit remains dead. This verifies the control circuit without starting the motor.
- Simulate an Overload: If safe to do so, simulate a fault by activating the test function on the overload relay. The contactor should drop out, and the "TRIPPED" LED on the CMA126 should illuminate. Use the RESET button on the module (or the overload relay) to reset the fault.
- Final Power-Up: Once control circuit testing is successful, de-energize the system, reconnect the main power to the motor, and perform a full functional test.
Conclusion
Installing the ABB CMA126 control module is a straightforward process that significantly enhances a motor starter's capabilities. By carefully checking compatibility, following the wiring diagram, and methodically testing each function, you can ensure a reliable installation that provides advanced control, clear diagnostics, and improved safety for your motor-driven equipment.
