What is the purpose of marshalling cabinets?
Marshalling means grouping of I/O. The marshalling panel is placed between the DCS system panel and the field instruments. By ordering the grouping of I/O panels as an analog input, Analog output, digital input, digital output and pulse I / O are made. From the marshalling panel the I/O signals are communicated to the system CPU / Drivers through Isolation / signal conditioners.
In the marshalling panel we can easily identify the Entry or Output and easy diagnosis can be made in case of failure
How Do Marshalling Panels Work?
The process of connecting field signals to process controllers is pretty standard, no matter what industry you’re dealing with. Firstly, the field signal wiring is brought to local junction boxes. These are similar to the junction boxes we’re all familiar with in our own homes. These boxes are then consolidated into more centralised junction boxes, which are in turn grouped into multi-core cables. The grouping is often done according to common characteristics, such as analogue or discrete, for example, or high or low voltage. Finally, these cables are brought into the marshalling cabinets. The output of these cabinets is then connected to the control system.
The main idea behind this marshalling process is to bring all the relevant instruments into the control room in a way that’s not only cost-effective, robust and durable, but which is also well ordered and easily maintainable.
Marshalling is usually carried out in one of three ways: cross-wire, fan-out and half-knit.