Power utilities use circuit breakers and fuses to interrupt power in the event of a fault on a transmission line.
The problem with fuses and circuit breakers is that once activated, a person is needed to visit to replace the fuse or reset the circuit breaker. The problem could be long term failure of equipment or just a short term, like a tree falling onto a transmission line or wires touching in high winds momentarily.
To solve the short term problem reclosers and sectionalisers are used to allow for a reconnection of the power which saves the need for field staff to visit the site. Management of reclosers and sectionalisers from a distance, using a telemetry system, assists electricity network operators manage the electricity transmission network.
Reclosers and sectionalisers are distributed throughout the electricity network. Simple reclosers are generally used to break and attempt to reclose the system based on voltage levels and a preset number of tries, perhaps 3 times, in the event of an overload condition. As reclosers are spread throughout the electricity network, only smaller sections of the network are affected for one recloser event, making it easier to manage the electricity transmission network. More complex reclosers have additional features, perhaps a system of current transformers so the voltages on the 3 phase lines, the status of the recloser and a record of the number of trips are reported.
There are also recloser systems with inbuilt RTU modules which allow a high level of measurement capability as well as some control capability. There could be data logging and remote control functionality, full directional protection for overcurrent, earth fault and sensitive earth fault, over and under voltage, over and under frequency and auto reclosing functionality.
Unidata can provide voltage measurement instruments with Neon Remote Logger systems. These would be appropriate manual, semi or fully automated recloser systems.
For more sophisticated recloser and sectionaliser equipment Unidata can provide a Neon Remote System utilising Modbus. The System can be set up so that the Neon Remote System (Neon Remote Logger and Neon Application Software):
• Acts as Modbus Master that collects and presents Modbus Slaves’ (reclosers and sectionalisers) data or
• Act as Modbus Slave that collects and presents reclosers and sectionalisers data as Modbus TCP for SCADA Modbus Master ingestion.
For management of reclosers a telemetry system is vital. In areas of cell phone coverage a Cellular 4G Neon Remote Logger can be used. Remote transmission system require satellite based telemetry systems such as the Neon Remote Logger Satellite – Inmarsat Satellite System which is “always on system” rather than a “satellite pass low earth orbit” system.
Unidata’s Neon Applications Software manages the telemetry coming in from remote reclosers and presents that information directly on the Neon Web system. As power utilities often have a central SCADA system the information could also be presented in real time using a direct SQL database interface or a Modbus TCP interface.
