what is electro mechanical energy
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Potential coil
A Voltage Coil Assembly consists of a coil
with many turns of fine wire and laminated core.
The voltage coil is designed to produce air gap
magnetic flux, which is proportional to the
applied voltage.
Meter stator
The stator of a Kilowatt-hour meter consists of
two sub-assemblies: a voltage coil and core assembly,
and a current coil and core assembly.
These two assemblies are precisely located on the
frame to establish an air gap through which the
meter disk rotates.
Current coil
A Current Coil Assembly consists of a relatively
few turns of large cross-section conductor and
a laminated core assembly.
The current coil assembly must produce air
gap magnetic flux, which is proportional to
the current drawn by the load.
Meter disk
A part of kWh meter that is directly driven by electromagnetic action.
Meter register
A part of the meter that registers the revolutions
of the rotor, or the number of pulses received from
or transmitted to a meter, in terms of units of
electric energy or other quantity measured.
Induction motor
A kWh meter is an induction motor that has stator which
consists of a voltage circuit, one or more current circuits,
and a combined magnetic circuit so arranged that their joint
effect, when
energized, is to exert a driving torque on the rotor
by the reaction with currents induced in an individual
or common conducting disk.
Determine Self Conctained(SC) and Instrument Rated(IR) meter
Self-contained (SC) Meter
A kWh meter that measures energy in a
certain loads and can sustain greater
currents, such as 100 amps, 200 amps.
Meter class found in the name plate: class 100 and class 200
Larger current coil cross-section conductor.
Instrument Rated (IR) Meter
A kWh meter that measures energy in a certain loads with
the help of an instrument transformer such as current
and potential transformer.
- Meter class: class 10, class 20.
- With pilot lamp for 3-phase meter.
- Smaller current coil cross-section conductor.
DETERMINE KILO WATT HOUR AND KILO WATT REGISTER
kWh meter
A Kilowatt-hour meter records the energy consumed by the loads;
and by accomplishing this measurement, an energy
seller can fairly charge an energy consumer for
the service rendered.
kW meter
A kilowatt meter that indicates
or records the highest demand (kW)
over a selected period of time, su
One of the difficult task of electrical engineer is how to design a banking transformer.
Banking means three single phase transformer combine to supply three phase line can be 240 or 480 volt by combining we loop each other end of the transformer bushing and secondary side.
The reason why banking of transformer born because not all single three phase transformer available in the market so in order to provide we bank a three - single phase transformer. And the question how to do that,1.) how many no. of wires to be looped, 2.) what kind of wire, 3.) what are the load limit of the transformer 4. The looping set – up of secondary side if 240 or 480 volt.
For further explanation and details, below are the example of 3-333 kva 240 v – 480 v transformer rated to supply 3 phase 230 volt, wye primary side and delta secondary line connection, ground mounted. Here it is..
1. Number of wires for looping secondary side :
where IL = Line current
IP = Phase current
KVA = Transformer size
V = voltage
IL = 3 x KVA / square root of 3 x V
= 3 x 333000 / 1.732050 x 230
= 2,2507.71 amperes @ full load
then
IP = IL/square root of 3
= 2,2507.71 / 1.732050
= 4343.47 amperes @ full load
since 336.4 AAC wire the current ampacity is 405 ampere
Number of looping wire = IP / 405
= 4343.47 / 405
= 10 or 11 conductors of 336.4 aac
see picture...
2.Kind of wire can be copper wire or all aluminum
3.The load limit of the transformer is 80% of the total KVA rated the 20% is the safety factor.
= 333, 000 x .80
= 266,400 VA
This is how the electrical line goes on see the following list.
1. The 138 kilo volt - 138 kilo volt or 138 kv is the inter connected
lines from different source like hydro, diesel, coal power plant. etc.
most of this line are installed across the forest using a tower with
a span between tower approximate 300 meters if it is in straight line.
The main purpose of this is to supply the step down transformer from
138 kv to 69 kv.
2. The 69 kilo volt - is the source needed to convert 69 kv primary
side to 13.8 kv secondary of the transformer 69 kv can be seen along
the highway or across the forest also but some utillty they did not
install across the forest for the reason that cannot attain immediately
in time of broken pole or construction the spanning of 69 kv between line
approximately 150 meters and erected and concrete pole 75 footer, with
no. 4/0 acsr or 336.4 acsr.
3. The 13.8 kilo volt - 13.8 kv is the output voltage of a three phase
Power transformer from what we called substation sometimes only one
transformer but it produced three to five feeders. This feeders is 13.8
or 13.8 kv 3 phase line can supply 3 transformer or 3 phase single
transformer but if you need single phase transformer 7620/240 volt much
better bacause you can tap only one line of a three phase line.
This week one of my team leader emailed me about the importance of stray voltage, how the affect specially in electrical. below are the following explaining stray voltage.
What cause stray voltage
For download
Stray voltage can be a human problem too!
A 50 MVA power transformer to transform 138 kv to 69 kv supplying 5 69 kva substation.
