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Questions tagged [three-phase]

AC power with three legs run 120 degrees out of phase

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2answers
55 views

Modelling 3-phase induction motor and filter for inverter output in LTspice

I am designing an inverter in Ltspice and am looking to have a simple circuit to represent the motor load and filter out the PWM harmonics in order to obtain outputs. The motor characteristics are: ...
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1answer
30 views

How to maintain a stable voltage on a Wind Turbine for Inverter

I'm doing some experiments on a wind turbine in my spare time. At the moment, my system runs well and I can measure good output values from my generator. For example: 38V @18Hz at 30 RPM 97V @37Hz ...
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1answer
56 views

What should be switching voltage rating of relay in a 380VAC 3 phase system?

I am hooking up a system where there is 2 sources of power available. One source is the grid power, and the other is a generator. The grid provides me with 3-phase 380VAC with a neutral wire; and on ...
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1answer
30 views

What is the difference between a rupture and the neutral conductor not existing from the start in star three phased system?

I have a pretty basic question. In three phased systems, I know that if the loads are equal, the neutal conductor has no role and can be removed, my question concerns unequal loads. My question is, ...
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1answer
83 views

How can 400V & 690V on e-motors result in the same power

Forgive my ignorance, but how can two 3-phase ratings on the same motor result in the same output power? The one I have is rated for 0.7kW in triangle for both 400V and 690V.
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1answer
30 views

Proper supply wiring for CNC router 4.1 kW 3Φ motor and 120 V accessories?

I'm building a CNC router table that has a three-phase 220 V spindle motor, and 120 V computer (and accessories). The spindle's nameplate: As you can see it tops out at 20.3 A @ 220 V. The VFD’s (...
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1answer
39 views

Line voltage and phase voltage question

​ In the question, why couldn't I just find Line current from Line Voltage? Is not Line Current=Line Voltage/Impedance? I know line voltage and line current aren't in phase, that the angle between ...
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0answers
71 views

How do I bring back to life a very un-excited 3phase 10kVa alternator

We are restoring a water mill and have recently got our 2 wheels turning once more. One of them is connected to an existing 3phase 10KVa alternator which although a little old seems to be in good ...
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4answers
192 views

3-phase 380 V to 3-phase 230 V

I have a portable bearing heater which works with 3-phase 230 V power supply. My power supply is 3-phase 380 V. Is there any way to convert the 3-phase 380 V to 3-phase 230 V? ...
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2answers
57 views

What is meant by the Sending end and Receiving end in 3 phase electrical circuits?

I do not understand the what sending or receiving end means in 3 phase circuit analysis. Aside: Also I am struggling to understand 3-phase just in general with respect to circuit analysis so if there ...
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3answers
65 views

Are three-phase contactors rated per pole or in total?

Are three-phase contactors rated per pole or in total? For example, have a look at this datasheet for a random three-phase contactor: datasheet In the datasheet it says that for AC-3 loads (1) the ...
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1answer
89 views

How is power out one side of 220 only - Problem is with incoming 3-phase. But how?

[EDIT] Can someone who understands what I wrote explain this? [EDIT 2] Sorry I didn't say I'm in the USA, the power is 110/220vac 60Hz. The input to the main power transformer is 3-phase, underground,...
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1answer
20 views

Can a DFIG operate in a synchronous speed?

A DFIG can operate in both sub and super synchronous modes. Can a DFIG also operate (stable) in a synchronous speed? If so, would the rotor current (as decided by IGBT switching) be DC since the rotor ...
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1answer
37 views

Reactive Power in grid side converter for Doubly fed induction generator

Does the grid side converter in a DFIG absorb/provide reactive power or is it reactive neutral? Also, what can we say about reactive power exchange in the rotor side converter?
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1answer
34 views

What are the d and q axes for induction machine?

What are the d and q axes for an induction machine (physical meaning)? I understand them for a synchronous machine but how are they defined for an IM?
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2answers
58 views

When tapping single phase power from a 3 phase service, how much power can safely be drawn?

I'm setting up a piece of lab equipment that needs 220v-260v to operate properly. The room it's located in has a a 480v 3-Phase service, in the form of a California Standard 50Amp twist-lock connector....
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1answer
54 views

“3 phase” Type of winding I am not aware of, help? not wye or delta, maybe eFed up generator?

I bought a few 30 watt 3 phase motor/generators in supposedly delta configuration from a ali express. the motor did have only 3 wires coming out, plus the manual stating it, I am pretty sure this was ...
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1answer
33 views

Calculating power with three phase?

I can't seem to find the answer I'm looking for, or perhaps I'm just really not understanding what I've read. I'm just confused. So, I'm a college student in a Theatre Production program and an ...
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2answers
70 views

Meggering Three Phase Motor (Phase-GND, Phase-Neutral, GND-Neutral)

When meggering a three phase motor, could someone please help me understand the values we would expect to see for a motor with no insulation or ground faults. From my understanding: Phase-GND: ...
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1answer
195 views

Instantaneous vector sum of three phases 120 apart is not zero?

Vector sum of equal 3 phases 120 degree apart is zero and serves as a neutral. However, while drawing instantaneous vectors of the three phases, they summed up all together to give a vector. I have ...
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0answers
50 views

Is there a cost savings associated with 3 phase power at the same device power requirement (kW)?

I am a Mechanical Engineer looking into purchasing an annealing furnace and have seen that some operate on single phase power while some operate on 3 phase power. I've done some research and have seen ...
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1answer
141 views

MOSFET H-Bridge Design - Capacitor/Diode/Resistor Selection

welcome to my first post! I am designing a small 3-phase Brushless DC Electronic Speed Controller (ESC). The design utilizes 3 half bridges and a FAN7388 driver IC. The FAN7388 datasheet has a ...
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1answer
116 views

Why use a star or delta connection instead of having a second output

I am winding my own small three phase ac alternator and have learned about star and delta connections. Should I use 2 three phase rectifiers to turn the current to DC or only one with a star ...
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1answer
50 views

3 Phase “Black Box” Load

I'm doing a few basic load calculations on a 3 phase circuit at work and I stumbled on a concept I'm not sure how to proceed. Let's say you have a 3 phase load and it is basically a black box. For ...
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1answer
86 views

480v motor, running like a bat out of hell.

I have a 480v motor that is connected to an auger. When the auger fills up, the torque from the motor continues to drive it and then just snaps the shaft clean in half. I am looking to build ...
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1answer
43 views

Multi phase vs single phase power factors

Are there any differences between calculating single phase and multi phase power factors? I'm open to general answers, but more specifically: If PF1=P/S, does PF3=(Pa+Pb+Pc)/(Sa+Sb+Sc)? Does ...
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1answer
45 views

3 Phase Voltage Imbalance

We're trying to setup rotary phase converter, and we're getting some differences in line voltage. The black reads 350 to ground while red and white read 120 to ground. This is all from a 220 input. ...
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4answers
924 views

Choosing proper wire gauge

I have a machine (a machine with seven three-phase motors) with this information on its nameplate: 3 Phases 400 V, 50 Hz 100 A, 40 kW I am wondering: Is 100 A for all three phases ...
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1answer
134 views

single phase 120V convert to 3 phase 208V

Can you convert 1-phase 120V into 3-phase 208V? If yes, whats the simplest way to do that?
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1answer
54 views

EV Charging tripping MCB

We have found that our two EVs are tripping the 32A MCBs in our Consumer Unit, but from my basic knowledge the 2*6.6kW chargers on UK 3-phase should only draw about 19A. I've measured the power ...
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1answer
107 views

How to design a 3-phase resistive load bank?

We are trying to design a 3-phase resitive load bank to test some step up transformers. We are receiving 3-phase 208v and stepping up to 3-phase 600V with 3-step up transformers wired in delta. Its a ...
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1answer
56 views

Three phase RC unit

I found this component connected in parallel with an inductive load ( three phase coil used to disengage a mechanism ) the load keeps heating and burning after a while ( had to rewind it ) and no ...
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0answers
27 views

Finding phase currents when given line currents.

Given a 3 phase system with unbalanced delta load, line to line voltage of 220v and line currents 15, 17, 19A (just chose random numbers for the sake of discussion). Is it possible to get the ...
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2answers
114 views

How can a switch that is in parallel with a lamp affect the lamp?

I've come across a faulty kiln (pottery oven) and since the wiring diagram seemed simple enough I decided to try to find the fault myself. However I'm dumbstruck by a strange behavior of a lamp. The ...
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2answers
56 views

Where to get started in designing a 3 phase motor circuit [closed]

I am required to design a circuit that requires a 3 phase motor which can be spin at a range of desired speeds and times. I know this will require: A 3-phase motor An inverter to convert single ...
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1answer
118 views

Why does line current equals the total apparent power divided by 3 times the phase voltage?

In this circuit with frequency of 50hz and line to line voltage of 400 V why is the current \$ I_A = S_t/3V_P\$ I don't understand the logic behind since there is one Delta connection, I understand ...
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2answers
234 views

Why is neutral required in three phase charging of Electric vehicles?

Talking about both three-phase AC as well as DC fast charging (wherein 3 phase AC is converted to DC) in EVs, I think that the 3-phase rectifier represents a balanced 'load'. Therefore I want to know ...
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1answer
60 views

kVA calculations

For electrical panels / systems with three phase electricity (red, yellow, blue) ~220/127. When using line to line we get 220 V is this considered single phase system or three phase? I know three ...
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1answer
45 views

Calculation of 3-phase power in Electric Vehicle Charging

I have a doubt regarding calculation of 3-phase power in EV charging. On the last page of the pdf in the link given below, the power calculation is done as 3 x 230V x 16A = 22kW. http://www3.fronius....
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1answer
34 views

Drawing power from only one phase of a 3 phase alternator

Note: I am busy learning about 3 phase alternators. A lot of my understanding is theory so I'm running through scenario's for better understanding. Scenario: Lets say we have a 2KW-220V-50Hz 3 phase ...
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1answer
173 views

Voltage between phases of 220V 3-Phase Generator with no neutral

I'm looking at a 220V-50Hz 3phase generator which has no neutral wire and 3 live wires. Am I correct in assuming that the voltage between phases will be 220V for this generator?
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1answer
48 views

What is the most efficient 3-phase to single-phase AC transformer for a home grid

So a friend of mine is getting electrical power installed for an urban site he bought, and I'm just trying to be a good friend by looking into this. The company doing the installation recommended he ...
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3answers
365 views

How are the individual homes connected in a 3 phase power distribution system (power grid) so that they have correct voltage?

For a single phase distribution system it's simple, each home has one wire coming from the neutral and one from the live, in turn each outlet has a live and a neutral wire. The live is 120V relative ...
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1answer
58 views

For induction motors, would one expect harmonics to be different between Delta and Y stator windings?

Given two induction motors with the only difference being that one is wound delta, the other Y, would I expect to see a different behavior if the source is a three phase voltage with harmonics?
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3answers
175 views

How does 3 phase AC generate more voltage than single phase? Aren't the wires connected in parallel?

If you connect two voltage inputs in series it results in a higher voltage, if you connect them in parallel it creates a higher capacity / max current, but voltage is unaffected. If you use 3 plugs, ...
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2answers
147 views

Why is the torque vs slip speed characteristic of an induction motor costant with respect to the frequency of the voltages applied?

I'm currently studying the induction motor and I have some troubles to understand which causes this thing. Let $$w_2 = w_1 - w_r$$ be the slip velocity and $$s = w_2 / w_1$$ be the slip, where w_1 is ...
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3answers
292 views

Current Transformer (CT) and Potential Transformer (PT) Sensors - How to Measure Electrical Power Usage?

I am not from Electrical Engineering background and so, does not have much idea about how energy power meters work. I want to measure electrical power usage of a three-phase induction motor. So, I ...
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3answers
157 views

How can a three-phase motor have 20 Nm of torque at 1432 RPM and 1.8 kW?

I am trying to work out the maximum torque a motor puts out to do some stress analysis on a structure, and I have just been given the motor details from the manufacturer. They said it produces 20 Nm ...
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0answers
79 views

BLDC phase voltage wave form

I am measuring the phase voltage of a BLDC motor as shown in the figure below. As the motor doesn't have neutral point, a virtual neutral point(VN) is created by the resistor network and three-phase ...
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3answers
83 views

Another question about power to homes in Europe

I have a couple more questions about power to homes in Europe. Our device draws between 12A and 45A (at 230vac) depending on its configuration. It appears that at the high end of the scale that will ...