Final Review Flashcards
What is the formula for induced EMF
E=BLV
How many degrees out of phase is induced EMF
180
at what degrees in an AC sign wave does the voltage equal zero
0, 180, 360
What is formula for a period
p=1/f
What’s the formula for frequency
f=1/p
how do you find the effective or RMS value
.707 x Vp
how do you find how do you find the average value
.637 x Vp
what kind of voltage do HVAC systems use
low voltage
what Components can you find in an HVAC system
fans dampers pumps valves and controls
what is direct digital control
control routines of standalone controllers done in digital form
How many control loops does a DDC have
30-40
what wattage classifies a wind system as a large wind system
exceeds 100kw
What is inductance
Opposition to change in current
what is capacitance
Opposition to change in voltage
As inductive reactance goes up current goes..
down
As inductive reactance goes up frequency goes..
up
what kind of losses are core losses
eddy current and hysteresis
What kind of Test is used for core losses
Open Circuit test
what are copper losses
I R losses
What kind of test is used for copper losses
Short circuit test
how many valance electrons is in a semiconductor
4
what Is the voltage drop across silicone
0.7v
what is the voltage drop across germanium
0.3v
what is the secondary rating of a CT transformer
5a (series)
what is the secondary rating of a PT transformer
120v (parallel)
How many diodes are there in half wave rectification
One in series with an AC load
how many diodes are there in full wave rectification
2-4 bridge type, biphase
what distance above the floor does unit equipment have to be
2 meters
what are the distance requirements for plugs
2.5 meters above floor and within 1.5 meters of equipment
do Exit signs have a height requirement
no
