Application Background Printer Friendly Version
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 problem such as 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 for one or more tries which saves the need for field staff to visit the site. Management of reclosers and sectionalisers from a distance allows / 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, 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 monitoring/data logging features. For example a system of current transformers maybe included so the voltages on the 3 phase lines are measured and recorded. The status of the recloser and a record of the number of trips could also be logged.
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 / digital inputs and output and data logging equipment with either the Starlogger or Neon remote Terminal range of data loggers / NRT systems.
These would be appropriate for some automated monitoring for manual or semi-automatic recloser systems
Unidata can provide Neon Remote Terminal telemetry systems for more sophisticated Reclosers and sectionalisers equipment using Modbus, either using Modbus master to read a Modbus slave RTU or using Modbus TCP where the Modbus Slave inputs from the reclosers are presented on a remote server as a Modbus TCP interface for easy ingestion to a SCADA system
For management of reclosers a telemetry system is vital. In areas of cell phone coverage the NRT GPRS/3G can be used. Remote transmission system requires satellite based telemetry systems such as the NRT Satellite- Inmarsat which is an always on system rather than a satellite pass system 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, and or it can be set up to provide alarms for specified recloser events. As power utilities often have a central SCADA system the information could also be presented in real time using web services or a direct SQL database interface or a Modbus TCP interface.