ABB SPAJ110C Earth-fault relay

The REF 543 feeder terminal can be used with different kinds of switchgear, including single busbar, double busbar and duplex systems.

The protection functions also support different types of networks, such as, isolated neutral networks,

resonant-earthed networks and partially earthed networks. 

The application area also covers medium-sized three phase asynchronous motors as well 

as protection and control of shunt capacitor banks used for reactive power compensation. 

In addition to protection, measurement, control, condition monitoring and general functions, 

the REF 543 feeder terminals are provided with a large amount of PLC functions, 

which allow for several automation and sequence logic functions, needed for substation automation, to be integrated into one unit.

The data communication properties include the following communication standards: SPA bus, LON bus, IEC 60870-5-103.

IEC 61850 via SPA-ZC 400. Profibus DPV1 via SPA-ZC 302. 

DNP 3.0 and Modbus communication with higher level equipment. 

Further, the LON communication together with the PLC functions minimizes the need for hardwiring between the feeder terminals.

Below is a side internal view of the EL mechanism and the associated anti-pumping component. 

When the opening pushbutton or coils are activated the opening shaft lever pushes down on point C of the anti-pump device.

This causes the device to side down slot D in direction of arrow B. 

Then the trigger portion A moves out from between the closing push-button and the closing shaft lever. 

So if the closing button or signal is held active and the opening button or signal is then activated.

The trigger A will pull out from between closing shaft lever and the closing push button. 

Once the open signal is released the trigger A will come to rest under the closing push-button and will 

not return between the closing shaft lever and closing push-button until the button or closing command is released.

The closing push button is operated by the closing coil (MC) directly by the shaft closing device.

This allows the anti-pumping device to prohibit closing by manual or electrical means.