AC power with three legs run 120 degrees out of phase

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2answers
50 views

Grounding a 30KVA isloation transformer

My company does audio visual services. When we use a single 120/208 VAC Three-phase "Y" power source for lighting, audio and video we get noise caused by the lighting dimmers injected into the audio ...
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1answer
65 views

How to determine phase angle of a three-phase circuit

I am experiencing difficulties with a question: A balanced three-phase load shown in the diagram is connected across a 380V, 50 Hz three-phase supply, ABC phase sequence. The voltage VAB is taken ...
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3answers
97 views

Line to Line or Line to Neutral voltage to calculate 3 phase power

I am confused as to whether or not I should use the line to line voltage on a 3 phase motor or the line to neutral voltage to calculate power? Would someone please be able to fill me in, and possibly ...
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1answer
50 views

Possible methods to control the voltage of a variable 3 phase power supply for an electromagnet?

The only solution I can think of is a three phase variable transformer, are there other methods? If so, what is the standard or accepted method to control the voltage of a variable 3 phase power ...
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0answers
48 views

How do I calculated total current on each line with an even number of circuits (unbalanced)

In the first example I was calculating the current each line would see for the purpose of sizing wire. An EE told me my calculation was wrong and that phase A would see 74A not 64A. I'm wondering ...
2
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3answers
633 views

Are normally open contactors virtually safe from failing closed?

Quick question: are normally-open contactors (which I assume are simply high breaking capacity relays) virtually safe from failing closed? I want to cut off a 400V 3-phase supply using an emergency ...
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0answers
41 views

3 phase currents come from 3 windings of a generator. But where is the neutral come from?

3 phase currents come from 3 windings of a generator. But where is the neutral come from?
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0answers
33 views

Exercise on a three-phase system where to evaluate the indication of the wattmeter

I have the following three-phase system where I have to evaluate the indication of the wattmeter W. Available data is: V = 380 ...
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0answers
39 views

3 phase stabilizer for single phase power

I just moved to a warehouse with single phase power (210 V? The power from the transformer is 3 phase.The power first goes to landlord's building before coming to the warehouse.) I have a Lioa dr3 30 ...
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1answer
62 views

Need to connect neutral wire?

In 3 phase machines have L1,L2,L3,N and PE(Protective earth).some time Neutral wire is not connected to the power supply.But,Machine have a neutral wire.What will happen if not connect neutral ...
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0answers
56 views

Wiring diagram and phase number of three phase transformer

Does anybody have an idea how to draw vector diagram of primary and secondary of a three phase transformer? For instance, if I need to draw vector diagram for Yzn5 diagram and then also draw the ...
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1answer
108 views

What happens if we run 415V 3 phase motor running on full load on to a 240V 3 phase supply?

I have a 415V 3 phase motor, but during emergency situation a 110V DC to 220VAC 3 Phase inverter comes into place. What will be the effects on the motor
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1answer
39 views

Single-Phase to Three Phase Cycloconverter

When my classmate report about cycloconverters. He discussed about different classifications and types of cycloconverters. He also discussed how Single-phase to Single-Phase Cycloconverters operate. ...
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1answer
150 views

Calculating single phase load from 3 phase power measurements

I need to record kW & kWh for individual phases on a circuit that has a 3 phase power meter that outputs the following data: Total for all three phases: kW kWh kVA kVAr power factor ...
0
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1answer
31 views

Mitigate the effects of magnetic induction heating in a three phase AC system

To mitigate the effects of magnetic induction heating in a three phase AC system, it is common practice to group the conductors and to keep them in the same raceway. Also, three phase power is ...
0
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2answers
227 views

Obtaining 240V from 480V 3-phase

We have a 480V 3-phase connection for a borehole pump, and we need to get a temporary 240V connection for lighting, no more than a few hundred watts. We are in South Africa which operates at 240V, ...
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0answers
284 views

Calculation of line-to-ground voltages from line-to-line voltages

I'm studying Electrical Engineering with the specification on Energy and Drive Systems in Germany. I currently have a task to develop a program, which gets some three-phase Voltages (line-to-line ...
4
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3answers
2k views

Y or Delta connections advantages / disadvantages

I have been studying three-phase systems for the whole course of a subject (on the first year of the university degree). I have finished now, and I know both "Y" (star) or "Delta" (triangle) ...
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1answer
111 views

Why would someone use an amplitude modulation ratio lower than one in a power inverter?

We had a test the other day, and there was this question: What is the minimum DC voltage required to drive a PWM, half-bridge, three-phase, power inverter to 4160Vrms. It should be possible to vary ...
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1answer
84 views

Three-phase system question

I'm solving some problems on three-phase systems. I'm doing pretty OK, but there is one problem that I'm not sure about the answer so I have some questions. We have a three-phase circuit connected in ...
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0answers
67 views

Three phase transformer question ?

we both agreed on the value of series impedance which is (12.82[82] ) however what i think he did wrong is the value of secondary reflected on primary since it is Y-delta 7967/480 = root(3) a ...
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0answers
30 views

Is it like that we can generate power in multiples of 3 only like ( 3 phase , 6 phase ) and can't generate in numbers llike 4 phase ,5 phase ? [duplicate]

does it has something related to symmtery ? Also why we prefer 3 phase more than others ?
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0answers
42 views

Three Phase Transformer

(Sorry for the bad drawing)... The picture contains three single phase transformers connected in star(both H.V. and L.V. sides). Now if i connect a load between the phase 'c' and 'n' keeping the ...
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1answer
172 views

How does 3 phase power operate single loads?

I am wondering how 3 phase power is used to power, say for example, light bulbs? If I have 3 phase power coming into my house, how are the 3 phase combines to enter the one prong of an electrical ...
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2answers
106 views

Three phase transformer windings

I have a quick question about three phase transformer windings. if I have a transformer that is Yd11 but I connect the generator to the d-side instead(primary side). Does it become Dy11 connected or ...
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4answers
885 views

Why do we need 3 phase power supply?

Why do we need 3 phase? For the reason that voltage will never be zero in 3 phase? OR we need high voltage?
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0answers
58 views

3-phase BLDC motor operation

I salvage motor from HDD, then I started googling around how to make it spin and found this video(there are good subtitles in English): https://www.youtube.com/watch?v=CMz2DYpos8w Here he just plug ...
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1answer
92 views

How does a multimeter sense whether it is measuring single or 3 phase voltages?

How does a multimeter sense whether the voltage we are measuring is single phase or three phase? It might be simple but I have no idea so please help me.
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2answers
330 views

Electric company supply single-phase or 3-phase?

Does the electrical company generally only supply single-phase in residential areas? i.e.: is 3-phase generally only available in higher use areas? And when 3-phase is supplied, do they have separate ...
0
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1answer
64 views

Field oriented control motor controller: is the measured Iq rms or the peak current? [closed]

Say the regulator regulates Iq to be 1A, is the actual motor current 1A RMS or 1A/sqrt(2)=0.707A?
0
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1answer
64 views

Three phase motor current verification

I want to verify that the quadrature current through a permanent magnet synchronous motor (PMSM) is actually the same amount as I commanded the field-oriented control (FOC) motor controller to push it ...
0
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1answer
80 views

Running single-phase through two or three windings of a three-phase inductor; why does the direction of the middle winding matter?

I have a three-phase inductor, MTE RL-00403, nominal 9 mH. I have some experimental results that don't make sense to me, which appear to be related to the fact that all three chokes share a single ...
1
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1answer
116 views

How to know if questions in an exam mean line, phase, or RMS voltage?

What is the difference between line, phase and RMS voltage? We get many questions where it is not mentioned whether the question is specifying line, phase or RMS voltage. I will attach some example ...
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6answers
3k views

Why are there only 3 wires on this power line?

When I was in Alaska, I saw a high voltage line, but I didn't see the Neutral. Is this because the water is conductive enough next to it to use as neutral? Or is it just two Phases. Where I ...
1
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1answer
117 views

motor Back EMF phase differences

I am reading though a product manual for an amplifier that I am working with. It says that if you view the motor Back-EMF while it is disconnected from the controller and spun in a clockwise direction ...
0
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0answers
138 views

Calculating Voltages in phases when a neutral fails

In the above star-connected three phase circuit the neutral is floating. I need to find the voltage across each load and which voltages are higher than 240 (Assuming the Line-to-line voltages are ...
1
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1answer
63 views

Calculating phase angles from symmetrical components

I'm getting the following values from a meter: ...
1
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0answers
71 views

How to add a desirable phase shift in the input from 3-phase ac mains?

I want to build a 12 pulse rectifier circuit. I know delta-wye or wye-delta transformers can be used to add phase shifts equal to the multiples of 30, but I don't want to use transformers. Is there ...
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3answers
1k views

Single phase from 3 phase generator

I got a good deal on a 3-phase generator, but everything I have is single phase. There's a sticker on it that says 230v 60hz. The output is a 4-wire plug. I did some testing with my multimeter and it ...
0
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3answers
88 views

Emergency 3-phase power supply in the event of power failure

I have two Magnum 400 10/20 drivers running two stepper motors. Peak power consumption is about 2 kW. In the event of a power failure on the 3-phase supply, I'd like to trigger a controlled emergency ...
1
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1answer
1k views

Calculate total apparent, average and reactive power in 3-phase

I am given a balanced 3 phase circuit question shown in the linked image. I am confused on the difference between apparent, average and reactive power and how each is calculated. This is my first post ...
0
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1answer
396 views

Three Phase Power. Phase Currents to Power and KVA calculations

I'm trying to learn a little bit more about three phase current, power and KVA. We currently have some hi-tech UPS power systems at work and I'm trying to ensure that they are adequately provisioned ...
2
votes
3answers
2k views

Three phase ground fault

Does a fault in ground of three-phase do more damage to home appliance than a fault in ground of single phase? and why? In a home with three phase input and single phase loads, fault in the ground ...
4
votes
3answers
136 views

What is proper polyphase AC terminology?

I'm not entirely clear on the proper terminology for polyphase AC systems. I hear it used informally, but I'm not sure what the proper formal names are, if there are any. How I've got it in my head is ...
3
votes
1answer
529 views

3 phase circuit, 3 x single-phase (hot-hot) loads: what ampacity?

I'm not an electrician (thus the question), but I'd like to know what is possible from a specification standpoint. Let's say we have a standard 3 phase power supply for a commercial building. We want ...
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2answers
112 views

how can i drive a motor with an inverter providing it's power supply? [duplicate]

I'm trying to drive a gyroscope that needs a 3 phase 400Hz 32v 0.7A power supply. i'm going to use an inverter to provide my supply(1phase to 3phase AC: LS-IG5A-0.75kw). i have 2question about it: ...
-1
votes
1answer
158 views

Making a three phase voltage source to drive a gyroscope

I'm trying to drive a gyroscope that needs a 3 phase 400Hz 32v 1A power supply. How can I provide that supply? It's one part of my university project and I'm a beginner in this field. I'd like to find ...
3
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1answer
134 views

Balanced three phase circuit Y-Y with neutral

Here is my equivalent balanced three phase circuit Y-Y with neutral: Rla + jXla is my line impedance by phase. L1 and L2 are my loads. The exercise is saying that L1 absorbs 180 W and 240 VAr, L2 ...
2
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1answer
176 views

Disconnectors Symbol in Single Line Diagrams (SLD)

where should the moving part of a disconnector be located when breaking gets applied, on the energized side or on the disconnected side? Is there any standard?? Suppose a non ring, simple grid and ...
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2answers
138 views

3-phase Inverter in single phase operation

I'm working on a standard (AFAIK) 3-phase, 6-pulse inverter. I'm testing it under single-phase conditions to see what the de-rating will be. My understanding: With everything else staying the ...