# Questions tagged [three-phase]

AC power with three legs run 120 degrees out of phase

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47 views

### How to determine time needed to stay in a voltage vector state in Space Vector PWM for 3 phase inverter?

I need some clarifications on how and when to switch between voltage vector states (for the sake of discussion lets take V1 and V2 in the image below). Below is the image of 6 possible voltage vector ...
58 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 ...
417 views

### Find impedence given per unit value-transformer

I really can't wrap my head around this. Three single phase transformers are connected to create a 3 phase transformer. They all have the same nominal values : voltage conversion : 1.2kV/120 V (...
307 views

### What will be the effect of putting a single phase load on an open delta transformer secondary?

Suppose I have an open delta transformer, 240 line to line secondary. I have a single phase constant power load I want to apply. I could apply it across either of the 'closed' phases and load that one ...
107 views

### Why are all my motors and transformers failing at this specific location?

At my job there is a vacuum oven. There is a 50 hp, enclosed cooling fan. that circulates N2 gas upon quench, the design of the unit runs 480 volts through a reduction transformer to 230 volts. This ...
27 views

### How to choose high frequency inductors for high voltage line filtering?

I saw these inductors 680 uH (RL-1294-680) in each power line like shown below. The line to line voltage is 480 VAC. The inductor used has a saturation current of 280 mA. So I suppose I shouldn't ...
62 views

### 24V, 3 Phase BDCM Controller Schematic

This may seem like a dumb question, but does anyone have a schematic for a BDCM controller. All I seem to be able to find are partial schematics or schematics that include a micro controller. My ...
78 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 ...
52 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 ...
179 views

### Confusion with applying KCL to three phase delta connection

Below is a 3-phase delta connected for balanced loads Z: Since phase to phase voltages(voltage across loads) have 120 degrees phase differences and since the loads have the same impedance we can ...
82 views

### Can we assume 230VAC in 3 phase system between phase and neutral?

If all devices connected to a 400V 3 phase power system are balanced and have a perfect power factor, can we assume the voltage between each phase and neutral is 230V? Why: I want to measure real ...
71 views

### Does using electronics with poor power factor affect the pulse power capability of a generator rated for a certain KVA?

The situation is such: There is a multi-pole, three-phase, permanent magnet generator (rated for 100 KVA, let's say) that feeds into a simple diode rectifier with a capacitive/DC Voltage load (...
127 views

### Generated current in a $3\times450$ VAC $60$ Hz $1150$ kVA generator

Let's say I've a $3\times450$ VAC $60$ Hz $1150$ kVA generator. How much current will there be generated when it runs at maximum capacity? MY WORK: The total Active power over a three-fase ...
66 views

### Non equal phase currents at nominal speed vector control Permanent magnet synchronous motor

I working on my implementation of vector control for PMSM. I'm having close loops over speed, current in d axis(flux loop), current in q axis(torque loop). I'm using MATLAB/Simulink for vector control ...
39 views

I'm given this transmission line problem in which I have a 3-phase transformer and I'm also given its impedence. I usually solve these problems using only one phase. So what should the impedence value ...
160 views

### Find transformer leakage reactance

For the short circuit test of a 3 phase transformer (star-star connected) I am given ( or have already calculated from previous questions) $$I=9720 A\\cosφ=\sqrt 2/2\\P=300kW\\R=0.001 (phase)$$I am ...
473 views

### When are positive-sequence and negative-sequence equivalent impedance the same?

One of the topics we covered in an introduction to power systems class was using zero/positive/negative sequence networks to analyze faults in networks. For many problems, this requires setting up ...
55 views

### Describe this type of rotor from a three phase induction motor?

After CNC machining the rotor, to expose the outer surface of the silicon iron, this proves to be exactly the same as the inner surface was (the one facing the core).Just plain electric iron rings ...
104 views

### Without converting the secondary side to “Y”, how would one solve this question?

The question: "A three-phase 230 V, 27 kVA, 0.9 PF (lagging) load is supplied by three 10 kVA, 1330/230 V, 60 Hz transformers connected in Y-Δ by means of a common three-phase feeder whose impedance ...
2k views

### Snubber circuit for 3 phase inverter designed for BLDC motor

I'm designing a motor controller for 3-phase BLDC motor. I'm using following components, Gate driver - IR2184 MOSFET - IRF540N The complete circuitry and output waveforms are available here. I have ...
558 views

### Trying to get the Run Capacitors right for my rotary phase converter. Getting Weird Results

I constructed a rotary phase converter from a 5 HP motor. The converter converts 220 single phase to 240 3 phase. Well, it is supposed to. I am getting some very odd results that I am wondering if ...
182 views

### Effect of the neutral current to a system when a 3-phase facility is used as unbalanced

Normally 3 phase-systems are used for balanced loads like in 3-phase AC induction motors. I know that in a balanced star configuration the total current across the neutral is zero. But what if each ...
395 views

### Two-quadrant sinusoidal (3-phase) PWM generation

I have a true sinusoidal BLDC driver, PWM of which works in Bi-polar, Complementary mode. I have to make it Uni-polar independent or Bi-polar independent, so the operation to become two-quadrant ...
578 views

### 3 Phase power logger with ADC and Raspberry Pi

I am building a 3 phase power logger with the ability to measure 3-phase AC and 2 DC inputs as well for a final year project. A typical application would be measuring a small inverter for a solar ...
83 views

### Measure 3-phase Power with Lecroy Waverunner

Please note that experience with a Lecroy Waverunner Oscilliscope is most likely required to answer this question. I'm attempting to measure the power draw of a brushless 3-phase motor with a Lecroy ...
93 views

### Purpose of resistors from phase to phase on 480V motor

I have inherited a project with a motor circuit that I cannot figure out the purpose of some resistors. It was initially designed for operation in Europe at 400V 50Hz. Since it is operating here in ...
330 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 ...
171 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 ...
79 views

### Rotation-switched active rectifier idea

Most of you will know how three-phase rectification works and how cool it is. My idea is: replacing the diodes in a three-phase full-wave diode bridge with MOSFETs, as in active rectification, and ...
223 views

### Missing phase 3-quadrant TRIAC-based solid state relay for 3-phase engine

First of all, I'm a simple mechatronics technician student first time posting here, so please don't mind if I say something that seems completely stupid, since I consider myself to be a total newbie ...
131 views

### Faulted phase detection

Currently I am studying about short circuit detection on long lines and I can't solve one task: I have line between two substations, and there is short circuit some where on this line. I know current ...
1k 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
36 views

### Calculating currents and powers on three phase 4 wires system

What do I use for phi in power equations?
81 views

### 12VDC to 3 Phase 400V

In order top prevent my seldom used deep well pump (3 Phase, 400V) I plan to daily spin it up for a few seconds. Where the pump is located, the is no power supply (I operate the pump using a ...
33 views

### How to estimate the power consumption of a motor when running at low load

I am trying to calculate the electrical power cost-saving of reducing the amount of time a machine runs idle (when the motor is running unloaded). From the meter data, the amps when idling is about ...
102 views

### AC water turbine

I am trying to use a water turbine from China to charge a lithium ion battery. The water turbine is rated to 10 watts. I figured that should be enough to charge the battery but I can only ever get ...
49 views

### Problem with Line to Line Voltage Output in 3 Phase Inverter MOSFET Bridge Circuit

I have a problem in my 3 phase inverter circuit output. Below, i've attached an image of my circuit. As you can see, i have 3 outputs. There are R, S, and T. So, i've measured line to line voltage ...
42 views

### Is a load bank always 3-phase or is a 4-phase possible?

I am designing a low voltage installation and the customer asked for a cell for a load bank. Now he drew this in 4-phase, but I did not encounter this before. Is this possible? I thought they were ...
35 views

We're in kind of a bind at work and looking for easiest / cheapest way to load an AC generator (Synchronous permanent magnet machine). We have access to a big 300A Mosfet module along with it's ...
40 views

### PWM phase voltage and current measurement for power consumption calculation for a BLDC MOTOR

I have been trying to log both voltage and current from the battery of an electric two wheeler for finding out efficiency at inverter, battery level.
41 views

### How to calculate R for an AC load on a 3-ph system

I'm trying to calculate the resistors in an AC dummy load for a 3-ph system. A simplified schematic can be found below. The idea is to switch (with regular AC 1-ph contactors) some resistors on each ...
58 views

### Circuit for Neutral point of 3-Phase mains

I wonder if the 'Neutral Point' as mentioned in the attached image is correctly labeled or not? Is there any mistake in this 3-phase circuit design? Edit 1: Also it looks like the 'Neutral point' is ...
86 views

### DIY 3-phase fast linear actuator

I have a need for a FAST linear actuator of which I may control position and speed reliably. I have already been looking into pnuematics, however it does not seem that this will fit my needs (I am ...
150 views

### IR2301 HO output staying on too long

I'm trying to make a 3 phase motor controller with IR2301 and IRFPC50 MOSFET. I connected everything according to IR2301 datasheet. For capacitors I’m using 10 uF (between VCC and GND) and 2.2uF (...
39 views

### how to get the line voltage of 3 phase delta circuit with power factor known at first?

In the following picture, it shows that a black box at right. the circuit inside the black box is a 3 phase load balanced delta connection circuit. the line voltage of it is 500V and the power factor ...
62 views

### Equivalent DC circuit of 3 phase induction motor

I'm currently trying to model a simplified circuit of an inverter + 3 phase induction motor. For now, I want to represent the DC link as an ideal independent voltage source. To keep this example ...
43 views

### Three-phase circuit with line impedance

I'm having some trouble with the first part of an exercise. If I only have V1, and Zl, how can I find what the line voltage V2 is equal to? So that, then I could calculate the phase currents A1,A2,A3....
53 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 ...