Power supplied by alternator

Question 1

𝜙

Answer 1

phase difference
between phase current and phase voltage where 𝜙 has a positive value when the
phase current is lagging the phase voltage and vice versa

Question 2

active and reactive powers for each phase formula sheet for both connections

Answer 2

𝑃𝑝ℎ = 𝐸𝑝ℎ 𝐼𝑝ℎcos 𝜙 and 𝑄𝑝ℎ = 𝐸𝑝ℎ𝐼𝑝ℎ sin 𝜙.

Question 3

total active and reactive powers for all 3 phase formula sheet for both connections

Answer 3

𝑃3𝑝ℎ = 3𝐸𝑝ℎ 𝐼𝑝ℎcos𝜙 and 𝑄3𝑝ℎ = 3𝐸𝑝ℎ𝐼𝑝ℎ sin𝜙

Question 4

can be rewritten in line V and I

Answer 4

𝑃3𝑝ℎ = √3𝐸L𝐼L cos 𝜙 and 𝑄3𝑝ℎ = √3𝐸𝑙𝐼𝑙 sin 𝜙.
Note that 𝐸𝑝ℎ, 𝐼𝑝ℎ, 𝐸𝑙 and 𝐼𝑙 are the RMS values.

Question 5

When Current Is in Phase with Induced EMF

Answer 5

both the voltage and current are rising and falling together — a typical resistive load. current in mag field -> lorentz force

Question 6

how is F affected by system

Answer 6

always opposes the rotation no matter what part of cycle ur in, even when emf and current are negative

Question 7

Why Do We Need Mechanical Power?

Answer 7

Because electrical current in the stator resists the rotor’s rotation, mechanical power and torque must be supplied to keep the rotor turning.

This is typically done using:

A prime mover like a turbine, engine, or motor.

The mechanical input is converted into electrical power output:
PMECH -> P electrical
​

Question 8

when current lags emf what happends to F

Answer 8

opposes F but some parts helps

Question 9

F when current lags or lead emf by 90

Answer 9

net force is 0, no net mech power consumed, ideal reactive power flow