Electronic equipment such as programmable logic controllers (PLCs), timing relays and coupling modules that can be affected by other components on ship electric network, are commonly used with conventional switching equipment on ship electrical system. For example, disturbances can be created by inductive loads when relays’coils are switched on or off.
To reduce the disturbance on ship switchinng elements, coils can be connected to suppressor modules, also called surge protectors, which are connected across the coils and dissipate the energy from the collapsing magnetic field when switched off.
Suppressor modules for relays and contactor coils
include the following:
- RC links – a resistor in series with a capacitor used with AC operated coils a)
- diode elements – provide excellent voltage limitation and are used for DC operated coils b)
- varistor elements – used for AC and DC operated contactors c) and achieve virtually unchanged switching times.
