ABB 6644424A1 Voltage Bus Monitor Assembly

The ABB 6644424A1, also cataloged as the 6644424A1 Voltage Bus Monitor Assembly, monitors DC supply rails within the ABB Bailey Infi 90 / Harmony Rack Power System (MPS3). It connects to the +5 VDC, +15 VDC, -15 VDC, and MCOM system bus connections and generates a low-true PF1 signal when any monitored voltage falls outside its specified tolerance.

Hardware Specifications

DC Bus Monitoring and PF1 Fault Signaling

The 6644424A1 supervises three DC supply rails referenced to the system common connection, MCOM. When a monitored voltage moves outside its specified operating tolerance, the assembly generates a low-true PF1 status signal.

The PF1 output provides a fault indication for integration with compatible system power monitoring logic. The supplied specifications do not define the individual voltage tolerance thresholds, signal timing, or output electrical ratings. These values should be confirmed against the applicable ABB hardware documentation before commissioning.

Frequently Asked Questions (FAQ)

Q: Which voltage connections must be wired to the 6644424A1?

A: The documented connections are +5 VDC, +15 VDC, -15 VDC, and MCOM on the system bus bar. Verify terminal assignments and polarity against the equipment wiring documentation before installation.

Q: What does the PF1 signal indicate?

A: PF1 is a low-true status signal generated when any of the three monitored voltage rails is outside its acceptable tolerance. The supplied data does not specify the precise thresholds or response time.

Q: What is the maximum specified input current?

A: The input current is less than 50 mA. Confirm the applicable power-system loading requirements before connecting the assembly.

Field Installation Guidelines

1. Verify that the assembly is compatible with the installed ABB Bailey Harmony Rack Power System (MPS3) configuration.
2. Isolate the relevant power source and follow the site's lockout/tagout procedures before accessing the system bus bar.
3. Identify the +5 VDC, +15 VDC, -15 VDC, and MCOM connections using the approved wiring diagram.
4. Inspect connectors, conductors, and mounting hardware for damage or contamination before installation.
5. Route signal wiring away from high-current switching conductors where practical. Maintain the equipment manufacturer's specified wiring separation and grounding practices.
6. Install the assembly on the designated DIN rail or mounting arrangement and secure all connections according to the applicable hardware instructions.
7. Restore power following site procedures and verify the monitored supply rails and PF1 status using approved commissioning methods.
8. Do not infer voltage tolerance thresholds or PF1 output ratings from the nominal rail voltages. Obtain these parameters from the applicable technical documentation.