Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [delta]

73 questions
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Why does a delta/wye transformer make 30 degrees phase shift ?

I'v heard that a delta/delta or Wye/Wye transformers do not make any phase shift. In delta/wye or wye/delta transformers, There is a 30 degrees phase shift between the primary and secondary coils. So, Why is there a phase shift ? and Why is it 30…
Michael George
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Can I drive a 3-wire-delta-input appliance with a wye-output transformer?

We have a high-current industrial machine rated for 3-phase at 230 V; the nameplate literally says "PHASES: 3Ph + PE", "VOLTAGE: 3X230VAC", and "FULL LOAD: 92A". There are only three input terminals (neglecting the PE, which is attached to the…
bernz
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I need help understanding the total impedance in a delta connection

I'm trying to upskill by teaching myself electrical engineering. I already have a degree in theoretical physics and pure mathematics so I don't mind math-heavy answers. While I don't find the maths of the electronics problems I've encountered so…
Jamie OM
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Three-phase motor Delta/YY connection diagram and windings troubleshooting

I am trying to troubleshoot this 1.4 kW three-phase motor and I'm unsure how its internal windings are interconnected or whether they are shorted. On the plate it says "Delta/YY 400 V", and I'm not sure what YY means. Most articles online describe…
Robert Lee
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Zero current assumption in star - delta transformations derivations

The formula used for star delta transformations are: $$ R_A = \frac{R_{AB} R_{AC}}{R_{AB}+R_{AC}+R_{BC}} $$ and $$ R_{AB} = \frac{R_AR_B + R_AR_C + R_BR_C}{R_C} $$ The normal way that these formulae are derived is by equating the expressions for…
Balu
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Why choose delta over star connection for a 3 phase motor with a VFD?

With respect to a particular application, why is it better to use a delta connection over a star? I have a motor/pump hooked up to a vfd in delta. For my application, Im required to adjust the flow rate of the water in the pipeline. The motor was in…
Luqmaan
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What are the Pros/Cons on the 30 Degree voltage phase shift between the primary and secondary of a Delta-Wye Transformer

I have searched this wonderfully informative website and learned much about Delta-Wye connections and why a phase shift in voltage would exist between the two. I am also aware that both Delta-Delta and Wye-Wye connections do not have this phase…
BLUEJAYS13
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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 many reasons, you don't have any access to the…
elimenohpee
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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 conclude that the currents Iux, Izw, Ivy across the…
user1245
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Dab vs Dac transformer

simulate this circuit – Schematic created using CircuitLab Why might one use a delta-wye transformer with the delta configured in Dab rather than Dac, or vise versa? Will this cause a difference in phase sequence? In Dab, coil A's non-polarity side…
nmorris
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Derivative of a waveform

I am self studying linear circuits and I came to a very basic problem. The problem: $$y(t) = e^{-t} u(t)$$ where \$u(t)\$ is the step function. Calculate the derivative of \$y(t)^{\prime}\$. My take is: $$ \begin{align} y(t)^{\prime} & =\left(…
Homer Jay Simpson
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Why is one current reading ~20% higher than the other two in a balanced high-leg delta load?

We are using eGuage watthourmeters to monitor the outdoor unit on five VRF systems powered by two different 3P4W 120/208V high-leg delta panels. The neutral is not connected to the outdoor units. We have connected the meters according to the…
LShaver
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Delta-Star Combination Exercise

This post is regarding exersise 4-8 from the following book: Hughes Electrical And Electronics Technology 10th Ed. Here it is: Let's focus on what I tried for solving part (b) : Since this is an exercise under the chapter for delta-star…
Stamatis
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Motors Delta/Star connections to VFD

I've selected 230/400V motors (delta/star) and corresponding 400V VFDs for pump motors. Now I've been asked why I haven't selected 400/690V motors (delta/star), that are the standard and usually connected in delta. The manufacturer says there that…
Yoda Master
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Why don't the currents clash in a 3 phase delta connection?

Consider 3 windings, a, b and c. L1 is connected to A, L2 to B and L3 to C. The 3 windings are then connected in delta. If we could freeze frame the voltage waveform where L1 and L2 are positive maximum and L3 is negative, what will the current…
Ph3ng
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