both six-phase and twelve-phase systems are not unheard of, and are utilized in some very large DC converters. Six-phase converters may use a delta-wye transformer, which provides 30 degrees of phase displacement. Zig-zag transformers provide 90 degrees phase displacment.
Long ago, electricity power meters (kWh, kVAh and kVArh) operated using eddy-current motors that spun a metal disk. The disk was connected via gears to a series of mechanical dials which could be visually read. The various windings for the eddy-current motors were wound such that the mechanical...
Hello all
I work at a BC Ski-hill... what I need is a method to quickly but accurately measure the depth of dense snow (man-made snow, some might call it ice). Traditional method of mechainically boring through to ground is slow, inaccurate & messy. New GPS based methods require detailed gps...
with lm324 you must ensure your circuit operating voltages stay well clear of the supply voltages. This is not a rail-to-rail op-amp.
With an instrumentation amp circuit show, it is very important to match the like-value resistors as closely as possible.
most 3-phase services use 4 wires : A, B, C, plus a grounded neutral
most 1-phase services use 3 wires : L1, L2, plus a centre-tap grounded neutral
electricity meters measure the total electrical energy, usually displayed in kWh
older electricity meters were electroc-mechanical, and used...
run a small air-compressor into the tank vent for a specific time (ie 10 sec). The air-pressure rise over that time will be inversely proportional to the volume of the air-space in the tank, and directly proportional to the fluid volume.
Here are a few more makes.
http://www.ctdrives.com/products/ac_drives.aspx"
http://www.abb.com/product/us/9AAC100211.aspx"
http://www.us.telemecanique.com/products/motor_control/Adjustable_Frequency_Drives/Index.html"...
VFD drives consist of 3 parts in series
1) a charge rectifier (moderately simple)
2) a DC capacitor bank (very simple)
3) Converter section : a transistor bridge array that converts the capacitor bank DC charge, into 3-phase AC (complex)
The charge rectifier does not care what the phase...
In Canada all revenue meters must be certified by Measurement Canada... same as the calibration of the gas-pump at a gas-station or a scale at a grocery store.
There are limitations & systemic errors typical in electronic meters that did not exist with old style eddy-current meters, but the...
transmission and distribution mean different things.
Transmission generally involves higher voltages >= 69kV, sub-station to sub-station & over long distances. Phase sequencing errors very unlikely.
Distribution brings the electricity from the nearest substation, down every street & back...
I have seen some larger commercial battery chargers (old designs) which incorporate a heavy-gauge DC series winding from the output, into the main transformer. The idea was that as the charger's DC current approached the charger's design current limit, the transformer iron was deliberately...
I run a small electrical utility, and can offer some insight
It is common to build distribution systems with some degree of redundancy. In this business, this is commonly done by building a series of distribution loops. This topology allows maintenance to be performed (via switching) with...
Attached is a photo taken of the after-cooler in discussion. I've added labels
Yes there are prints (paper only). The system was designed by an engineering firm that is no longer around.
Over the past week I've come to believe that this unit was designed more for stripping out water droplets...
Thanks again for the replies
Whenever we are running these air compressors we are also running high-volume water pumps up to 1750 psi (it's a mountain). So no problem getting water to the top of a 12m aftercooler.
We can feed the aftercooler outer jacket via a PRV, with an outlet ball-valve...