week 2 (chapter 2) Flashcards
changing any two of the three phases in a three phase motor will effect it how?
direction of rotation
what are three advantages of three phase over single phase systems?
- 73% more power for 50% conductor increase
- less pulsating force
- smaller and less expensive equipment
what is the degree of separation for the coils of a three phase motor?
120 deg
there is a ________ _______ between any two phases at any time throughout the cycle of a three phase sine wave.
potential difference
in a three phase sine wave, one phase is at ______ and the other two are?
zero/providing power
in actual practice, within a three phase generator the ____ are stationary and the ________ ____ is rotating?
coils/magnetic field
what two configurations can three phase generators be connected in?
delta and wye
what is the square root of 3? why does it matter?
1.732/used to calculate voltage difference between phases and the neutral
in a _____ system, coil and phase current are the same.
WYE
in a _______ system, system voltage is the same as phase voltage.
DELTA
in a delta system, phase current is higher than coil current by how much?
a value multiplied by 1.732
on historical _____ systems, it was thought a lineman could barehand a phase safely with no electrocution risk.
DELTA
which system is the one of choice for today’s utilities?
WYE
WYE systems can serve a given load with less or more current than a DELTA system?
less
where do DELTA systems exist today?
isolated areas