Today I had to install a datalogger on the network transformer at the tunnel drilling site for the Puhoi tunnel, north of Auckland on SHwy 1 to monitor for voltage dips on the 11 kV supply line which is at the end of a long rural line.
Also I had to load the fuses and do the 11 kV switching on the network switchgear as well as livening up the two mining transformers on site for the soak test, polarity, phase sequence and voltage checks.
The total consists of 4 transformers.
Network TF.3Ø 500 kVA. 11 kV / 240-415 Volts. 26.5 / 696 Amps.
Customers transformers.
Local site supply TF. 3Ø 750 kVA. 11 kV / 240-415 volts. 39.4 / 1042 Amps.
Machinery TF. 3Ø 600 kVA. 11 kV / 433 Volts.
31.5 / 800 Amps. ( 250 Volts P - N ) Dyn 11. impedance 4.41%.
Drill TF. 1000 kVA. 11 kV / 1050 Volts. 52.5 / 550 Amps. ( 606 Volts P - Screen ) Dyn11. impedance 3.92%.
The drill is driven from 3 x single core neutral screened cables.
Anyone else has some non standard voltages?
I can sent photo's of the TF. nameplates if anyone is interested.
