Control Circuit Separation
Separating the control voltage from the power circuit with galvanic isolation. It is usually provided by a control transformer or a separate direct current source; the aim is touch safety, keeping fault currents from being carried onto the control line, and reducing noise.
On a receiver supplied with 220V AC, if the control and power circuits share the same voltage, mains voltage is present at the terminal and there is a touch risk during maintenance. When separation is applied, the control side stays at low voltage.
- Isolation: an isolating transformer prevents earth faults on the power side from being reflected into the control circuit.
- Earthing arrangement: by earthing one end of the control circuit, a single insulation fault blows the fuse instead of causing unintended operation.
- Voltage drop: on long control lines, cross-section and distance are assessed together so that the coil drop-out threshold is not approached.
- Separate protection: the control circuit is given its own fuse.
According to the AXI product data, the SF100 and ST100 receivers can be supplied with 12/24V DC or 220V AC; for the SF200 only 12/24V DC is given. Choosing a direct current supply simplifies the panel design, since it solves the separation at source level.
The context in which this term is used: Wireless Crane Remote Control Selection Guide