3 phase Definition and 126 Threads

Hi All, I have access to a 15kW VFD for little money. I only have single phase 240 vac at home, and need to drive a 10kW motor, 3 phase, 415v. I have been reading that 3 phase input VFDs can be run on single phase, but they must be derated by 50%. This would mean a 20 kW VFD. Also, it is a...

Homework Statement I have an exam coming up and one of the practice questions is as follows A 415V 50Hz three phase supply energises a balanced star-connected load through a three phase feeder with a per-phase series impedance of Zline = ( 0.165 + j0.413 ). A power meter at the source end of...

Hi I have been trying to find the types of equipment required to protect 3 phase generators+transformers for a while now but I just cannot seem to find anything. If you could help me out and give me examples of the equipment it would be greatly appreciated Thanks

3 Phase Rotor / Stator Swapping ? I have been toying around with the following idea : (specific application project) Normally a stator is the external housing of a motor and is fixed to a structure - the rotor is the shaft through the middle of this stator etc. and is rotating at ...x... RPM...

Hi guys I have been testing a brand new 250kw 3 motor wired in delta. I have it connected to a 170 amp vfd with no load for testing. It draws 105 amps at 50hz and is balanced. Intermittently the motor makes a strange that i have not heard before. It sounds like a spoon taping another...

Dear all, This is a newbie asking for some information. Actually, we have 1x30HP, 2x10HP motors working at our workplace. When we start the motors there is a lot of torque generated due to which our grid supply charges us penalty every month. We need information about the device(s) that...

Hello, For our final lab we will be given a box with three wires, the neuter is missing. In the box there is a Y or delta configuration and we can use everything to find out if it is a Y or a delta configuration. So, voltmeters or watt meters, or even something like tin foil. Can someone...

Hello everyone, Thanks in advance for any wisdom you can offer regarding this matter, I just joined physicsforums.com and am now wondering why I haven't been a member all along... My crudentials: I'm an electrician that went part way through college for electrical engineering, however Its...

Homework Statement Three load each having a resistance of 16 ohms and an inductive reactance of 12 ohms are wye connected to a 240V three phase supply. Determine: a) the impedance per phase b) the current per phase c) the kVA total d) the Power Factor e) the kW total Homework...

3 PHASE INDUCTION MOTOR A 15 hp/230V, three phase induction motor has a full load current of 42A per terminal. 15HP= 11kW find: a) Full load kVA input b) If the full load power factor is lagging 0.85, what is the kW input. My question: How do I know whether its connected Wye or Delta?a) kVA=...

I have a question and am wondering if reddit can help. In a 3 phase power system, the overall total power is meant to remain constant. Now, I understand that the individual powers are meant to vary, but as a system, it is supposed to be a constant. If you could take a look at this "code" if you...

Why is it that we accept triple-n harmonics in the output voltage spectrum of VSCs? Assume we are using SPWM where the frequency modulation index is selected to be a large odd integer multiple of 3. Thanks again!

Hi all, I would like to install Capacitor Bank into my control panel board which contains of few 10HP induction motors. Currently I'm just able to measure the Ampere for every induction motor by using current meter. How to calculate the reactive power for 10HP 3phase 4pole induction motor by...

1. Statement A star connected load of 3300 kVA at 18 kV and a power factor of 0,8 lagging is supplied by a three-phase transmission line having a resistance of 4Ω per phase and an inductive reactance of 7Ω per phase. Determine: a. the sending-end voltage b. the percentage regulation c...

I am building an on-board generator for a small aircraft (AUW = ~ 10kg). The fuel motor is rated at 1.8 kW and it directly drives a 3 phase AC motor. The rpm will be regulated at roughly 8k so I think the frequency of the AC output will be around 133 Hz. The AC motor produces 1 volt per 260 RPM...

Hi, I think I am correct, but just wanted to check. We have some furnaces and I want to work out what power they run at. I have a scope with a current clamp and voltage probe. I have set the scope to read out power and power factor. That is where my problem lies, I think. I should have set...

Hi! I have one question. Assume a source of about 20KV and 4 Amps. This source needs to be connected to a transformer in order to vary the voltage and current into desirable amounts. The ideal transformer takes the input power and gives out the same power as output. My question is: I...

Hi folks, I'm a Mech Eng who is trying his hand at some Electrical design so please forgive my ignorance. My set-up is as follows: I have a 3 phase source powering a 3 phase induction motor. If I then went half way along my power cable and put a separate current transformer on each of the...

When the voltage / frequency is maintained constant in 3 phase Induction motor i.e. flux is maintained constant by changing the voltage and frequency in same proportion, What is the torque proportionality equation. Whether Torque is proportional to Slip X Frequency or Torque is...

while reading about sequence networks, I realized this. Suppose I apply same phase to the primary of Star-Delta transformer, say instead of applying A,B, and C phase to the three terminals, I mistakenly apply A,A and A phase to all the terminals, <Neutral is applied appropriately>. Then since...

So I have been trying to figure out the actual advantages that a 3 phase generator has over a 1 phase generator. I have been trying to find a mathimatical proof as to why 3 phase is more efficient. I have looked everywhere and have not been able to find an answer. I know how to prove that 3...

So I am trying to figure out how to wire a three phase generator. I understand the WYE connection, but I am stumped about the load connections and specifically what to do then. The generator will be connected to a wind turbine so I will be needing to charge batteries. So my main question is...

So I am trying to figure out how to wire a three phase generator. I understand the WYE connection, but I am stumped about the load connections and specifically what to do then. The generator will be connected to a wind turbine so I will be needing to charge batteries. So my main question is...

Hello all, I have a 3 phase Variable frequence drive that requires an input voltage of 380-480VAC. I would like to test what would happen if I apply 300VAC to the drive. I have access to 208V and 440V. Is there anything I can do to obtain 300V? I have thought about a variable power supply...

Hi We have a project where we have to install an HVAC system but only a 3-phase supply is available. While that is fine for the motors inside the unit, it means that there is no neutral available for the control circuitry. I am aware that a "zig-zag" isolating transformer can provide a...

Greetings, According to Faraday, a single phase generator ideal output voltage is: V = N*A*2PI*RPM/60*B Then should a three phase be: V = N*A*2PI*RPM/60* B * SQRT(3) ? I'm trying to build a spreadsheet to get ballpark numbers for simple variable speed generator design, but having difficulty...

Hi, i just need some help with something, I have been given a question to solve. I need to find a) sending end current, b) sending end power factor c) full load active power losses of a three phase "double Circuit" transmission line...I know how to calculate all of those for a three phase...

A short question: Why and how is the line current equal to the phase current in the 3phase- 3wire system?

This is my first post on this forum and my electronics education has a long way to go so please forgive me if this is a dumb question. I've been learning about 3 phase power lately and I have been wondering if an experiment I want to do is worth it. Anyway, I want to rewind a 3 phase...

Homework Statement Calculate the line current required for a 30kW 3 phase motor having a power factor of 0.85 lagging if it is connected to a balanced source with a line voltage of 440V.Homework Equations P=√3Vl*IlCos ∅ Il=\frac{P}{√3VlCos ∅} P=Average Power Il=Line Current Vl=Line Voltage...

Why industrial motors etc need 3 phase power and something like a TGV (high-speed train) only needs 1 phase (25 kV AC railway electrification), and yet its capable of such performance?

Hi all, I have a 90kva 3 phase 440volt/220volt stepdown transformer. When i test on no load ie secondary not connected to anything but the power is on, i get 220v between phases but to Earth or ground i get 1st phase 150volts 2nd phase 104volts 3rd phase 150volts Does this mean my...

Hi there, i'm trying to do a technical paper on converting 120 volt single phase to 440 volt 3 phase for a diving tender boat. Does anyone know what things i should be concerned about when trying to convert the power. The boat usually runs in generators alongside but, i was hoping to hookup...

in three phase rectification at say 50 hz the dc output ripple will be in 6 times the supply frequency, when choosing an inductor to smooth this ripple to <20% of the output frequency,what formula should be used. also if say the supply frequency was 100 hz is it correct to persume that the...

Homework Statement List two causes of reverse rotation in a three phase motor. Homework Equations The Attempt at a Solution I've already listed incorrect phase termination as my first solution, but I'm stumped on the second. These are supposed to be "quick fix" solutions, no...

[FONT="Verdana"]What happens if an big AC induction motor is running with full load an your suddenly reverse the 3 phase?

My home is supplied by 3-phase electricity. When the electricians installed the system, they made guesses at how to balance the loads across the 3 phases. The country that I live in limits the amount of power available through each phase with a closed box that trips out if ANY ONE of the...

Hi there all I'm looking to measure current in 3 phase cables, and would like some advice on any current clamp models you'd like to recommend. However, I'm not entirely certain on the method as well; I've used current clamps before on single phase cables, and I'm aware that you need to clamp...

When I have the Vphase (254 V) S phase (6.2KVA) and I (24A) ? Help !

If you have a 3 phase 4 wire distribution where the 3 phase conductors and 1 neutral is inside a pvc conduit, how would you model the force of the electromagnetic field at a certain distance away from the conduit? Assuming the loads are balanced, the currents would sum to zero on the...

my outlet reads 240 across any two of three leads. Can I assume it is 240 3phase rather than 460 which I also have at the same location. What would 460 read across the leads? Thanks Tom

Hello Everyone, I have a question about how power amplifiers output their power to 3 phase motors. I am using a copley xtl power amplifier to power a 3 phase motor, i want to use a relay to interrupt that motor current but I am not sure how to size it. If the peak output of the amplifier is...

Hi there, Need your help guys. I need to convert the attached 3 phase power supply to a normal UK 240v power supply. Can this be easily achieved without major costs in converters/transformers?

3 phase joining in series, possible?? Hello good people. I need to run a brushless motor on an esc but the equivalent speed controller is three times the price of motor. I was wondering if it is possible to connect TWO output 3 phase current in series in an effort to stack up the voltage...

Ok... This is a simple question that I'm having a hard time with. I'm forgetting something that I learned and I want to clear it up... I know that a 120/208 3 phase system has 3 hot leads that are 120 degrees out of phase with each other with respect to the neutral. If you multiply 120 X...

I have just completed a course in Transformer Design. But I am now surprised at a result I found. For Handling Same Power (Say 15 Kva) at around same efficiency, 3 phase transformer are more heavier and costlier than single phase transformer. Although, The Copper Weight Decreases in case of...

Homework Statement A three phase, 6-pole, \Delta connected induction motor is rated 208V, 60Hz. It has R_R\,=\,5.2\,\Omega, R_S\,=\,2.2\,\Omega, X_m\,=\,220\,\Omega, X_{lr}\,=\,7.5\,\Omega, X_{ls}\,=\,2.3\,\Omega. Calculate the starting torque and both phase and line currents when the motor...

Hi, I am trying to understand the concept of the VFD & the AC motors running on three phase . I have briefed about the concept involved with the VFD what i understood;--- Torque --- directly proportionalt to applied V^2 speed --- directly proportionalt to frequency One way to...

Homework Statement A star-connected, 3-phase, 100kVA, 415V, 50Hz synchronous motor having a synchronous reactance of 1.2ohms and negligible resistance operates at its rated terminal voltage, rated current and per-phase field-induced emf of 228V. Determine the power factor. The excitation...

Hi guys, I would really appreciate some help with this problem(probably quite easy for anybody with Electrical Engineering experience). Thanks in advance Homework Statement A 415V, 50Hz, 3-phase supply is connected to a 3 phase load of 10kw with a power factor of 0.8 lagging. Find the...