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🧰 Panel Wiring Guidelines

🔹 Busbar Planning

There should be a total of four separate power supply circuits in the panel.

1. BBAS Busbar (Logic Power Supply)

A dedicated power supply busbar must be provided to power the IO Module, IM Module, CPU, and Ethernet Switch.

This busbar should be named BBAS(+) and BBAS(-).

It must remain completely isolated from all other busbars.

Important Notes

  • When measuring voltage between BBAS(+) and any other busbar’s (-) terminal using a multimeter, no voltage should be present.
  • Similarly, no voltage should be measurable between BBAS(-) and any other busbar’s (+) terminal.
  • This busbar must not supply power to any field devices. It is meant only for powering the logic side of system components located inside the panel.

2. BBS Busbar (IO Module – Field Interface Side Power Supply)

For DI relays, the contact side pole should be connected to 24V (+), and the NO terminal should be wired to the DI Module’s FTA.

The (-) terminal at the DI module’s FTA representing field-side power return should be connected to 24V (-).

This circuit shall be powered using a busbar named BBS(+) and BBS(-).

  • The same BBS busbar will be used to Loop and connect all (-) terminals of the coil side of DO relays.
  • The (+) terminal at the DO Module’s FTA (field-side power) should also connect to BBS(+).

Just like BBAS, When measuring voltage between any terminal of BBS and any other busbar using a multimeter, no voltage should be detected.

This busbar also does not power field devices directly.
Like BBAS, it is strictly used for supplying power to the field-interfacing side of IO modules inside the panel — isolated from the logic side, but still internal to the panel.

3. BBF Busbar (Power Supply for DI Relay Coils)

For DI relays, the (-) terminals of the coil side should be looped together and connected to BBF(-).

Power will be taken from BBF(+), routed through a fused terminal in the marshalling area, and then supplied to field-mounted sensors like proximity sensors.

The return wire from the sensor will come back through a non-fused terminal in the marshalling area and connect to the (+) terminal of the DI relay coil.

Isolation Check: - No voltage should be measurable between any terminal of BBF and any other busbar using a multimeter.

4. BBSOV Busbar (For Solenoid Valve Operation)

If a solenoid valve needs to be operated in the field, an additional power supply busbar must be used, named BBSOV(+) and BBSOV(-).

🔸 Power Supply Planning

As per the above busbar arrangement, at least four separate power supplies will be required in the panel.
The recommended naming convention is:

Circuit Type Primary Redundant
Logic Power (AS) PS-AS1 PS-AS2
IO Field Power (S) PS-S1 PS-S2
Field Sensors (F) PS-F1 PS-F2
Solenoid Valves (SOV) PS-SOV1 PS-SOV2

These names are based on the provision of redundant power supplies.

If redundancy is not implemented, only the first unit (e.g., PS-AS1) may be used. However, using redundant power supply for AS circuits is highly recommended.

🔁 Redundancy Guidelines

  • Always use a redundancy module when redundant power supplies are employed — especially for PS-ASx and PS-Sx.
  • For PS-Fx and PS-SOVx, if compromise is acceptable, a diode module may be used instead of a full redundancy module, since these circuits typically power non-sensitive components like proximity or smart sensors.

Ideally, even these should be powered from reliable supplies, but field experience suggests that their failure rarely results in complete system failure.

⚠️ However No compromise should be made with PS-ASx and PS-Sx, as they power sensitive control system components. Failure in these circuits can impact the entire system.