Evolving changes to the power demand profile caused by low energy lighting, heat pumps, electric vehicles, etc. as well as single and three phase solar and wind generation connected at LV has led to a need to monitor the LV network to assess the impact and to predict future changes.
To meet this need eMS has designed a specific instrument for logging the real and reactive power on each phase of each feeder from a substation as well as the voltages, currents and relevant power quality (PQ) parameters like harmonics and flicker. The number of feeders is extensible and the present limit is 12. The measurements are max, min and average values every 10 minutes and there is an option to increase this to every 1 minute. The measurements are synchronised to the system clock.
For systems located in a substation sub.net-SLV is supplied in a wall mounting enclosure. This is sized to suit the number of feeders. The standard enclosures are steel but if the busbars are exposed there may be a safety issue during installation and GRP types can be used instead.
For LV locations the communications is via wireless modems. Regular power and PQ reports can be sent via email with data attachments in Comtrade or CSV format. Alternatively the data values may be sent directly via Modbus or DNP3 protocol to a central server.
sub.net-SLV can also be located in a ground mounted or pole mounted transformer. The system is powered from the VTs and a battery backup option is available. The phase currents are monitored by Rogowski probes fitted round the fuse housing or cable.
HV & MV logger
sub.net-SLV may also be used in higher voltage substations. For these installations a transducer is fitted in each feeder bay and these are looped together and connected to sub.net-SLV. This simplifies the VT & CT wiring and supports a variable number of feeder bays.