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Level 3 Electrical, BCIT > Formulas > Flashcards

Formulas Flashcards

1
Q

What is the formula for finding El in a Wye system?

A

El = Ep x root 3

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2
Q

What is the formula for finding Il in a Delta system?

A

Il = Ip x root 3

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3
Q

What is the formula for finding VAt on both Delta and Wye systems?

A

VAt = El x Il x root 3

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4
Q

What is the formula to find total power delivered on both a Wye and Delta system?

A

Pt = El x Il x root 3 x PF
Or
Pt = El x Il x root 3 x cos theta

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5
Q

What is the formula to find power out of a motor?

A

Pout = Pin - losses

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6
Q

What is the formula to find copper losses?

A

I^2 x R

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7
Q

What is the formula to find Regulation?

A

Enl - Efl / Efl x 100

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8
Q

How do you find E gen of a short shunt generator?

A

V drop across armature resistor + V drop across shunt winding

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9
Q

How do you find efficiency of a generator?

A

Add both of the wattages produced in the generator (armature and resistor). Divide terminal power by the armature and resistor power.

Pa + Par / Pload

Or Pout / Pin

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10
Q

What is the formula for Output Voltage of a generator?

A

Egen - IR drop in armature and brushes

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11
Q

What is the formula to find frequency?

A

F = P x N / 120

Frequency = number of poles x RPM / 120

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12
Q

What is the formula for the 1 wattmeter method?

A

Pt= W1 x 3

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13
Q

What is the formula for the 3 wattmeter method?

A

Pt = W1 + W2 + W3

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14
Q

What is the formula for the 2 wattmeter method?

A

Pt = W1 + W2

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15
Q

Formula for finding synchronous speed in AC motors

A

S = 120 x f / P

P is number of poles per phase

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16
Q

Formula for rotor slip

A

Slip % = sync speed - rotor speed / sync speed

Slip amount = sync speed - rotor speed

17
Q

Formula for finding rotor frequency

A

f = P x Sr / 120

P is number of stator poles
S is slip speed

18
Q

How do you find impedance of a transformer?

A

E short circuit / E rated

19
Q

How do you find efficiency of a transformer?

A

Power out / power out - power losses

20
Q

How do you find fault current of a transformer?

A

I full load of the secondary / %Z

21
Q

Horsepower of an AC motor

A

HP = (torque x speed) / constant

Level 3 Electrical, BCIT (7 decks)

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