Three Phase Power
SECRET FORMULAS
Alternator
Motor
Misc.
100
When calculating values, what number do you multiply by, when you have the line values
1.732
100
(VA)/(EL x 1.732)
Supply Current (IL)
100
The Direct Current that is am input to the alternators rotor is the ...?
excitation current
100
In the consequent pole motor, when the polarity of half of the pole winding's is reversed, there by effectively doubling the number of poles, the motor speed will ..??
Cut in half
100
In a three phase alternator, the direction of magnetic field rotation is also called
phase rotation
200
The power in a three phase system...
NEVER falls to ZERO
200
(120 x F) / (P)
Synchronous Speed
200
Connection the the armature of an alternator is normally done by using
Sliprings
200
The wound rotor induction motor, has a ____ starting current, _____ starting torque, making it very popular.
Low, high
200
What tool is used to check the phase angle difference?
Synchroscope
300
When calculating values, what number do you multiply by, when you have the phase values
3
300
(P x SR) / 120
Rotor Frequency
300
In order to increase the efficiency of the cooling, some alternators operate in an atmosphere of ..?
Hydrogen
300
If one phase of voltage to a three-phase motor opens, the motor may slow down, overheat, or possibly stop. This is known as what?
Single Phase
300
An alternator containing eight poles per phase is turning at 2300 RPM. What is the output frequency?
153.3333333333333333333333333333333333Hz
400
The three phase connection in which one end of each winding is connected at a center point.
WYE
400
(746) x (HP)
Power Out
400
If one alternator, is not sufficient enough to power a load, another can be added to the circuit. The second alternator needs to be connected how?
In parallel
400
Selsyn motors operate on what kind of voltage?
Single Phase
400
The non-rotating part of an alternator is called the
stator
500
The three phase connection in which each end is connected to form a closed loop.
Delta
500
How do you find voltage unbalance ?
Find Avg of the voltages
Subtract biggest difference from average
(100 x Difference in greatest number) / (Avg. Voltage)
500
In order to limit voltage when the rotor DC excitation is removed, what must be used
field discharge resistor or diode
500
What connection is pictured?
High Voltage
500
What does alternator do?
Converts mechanical input into alternating current