HVAC 118 ESCO/Test Review
What is generally considered to be the maximum allowable (plus or minus) supply voltage variation for a conductor?
5%
Two 120 volt incandescent light bulbs are wired in series, one is a 60 watt bulb, the other is a 4 watt bulb. The result would be
60 glows 4 dim or only 60 will light
What is true about current
Current flow will increase when voltage increases
The safety ground conductor is almost always this color
Green
In Ohms law what is the symbol for current
I
What type of meter uses its own battery
Ohmmeter
Like charges do what?
Repel one another
What is the term used to describe the output side of a transformer?
Secondary side
Honeywell Smart Valve
Sensor: flame sensor Description: 24 volt HSI lights the pilot, pilot lights the main burner
Hot Surface Ignition (HSI)
Sensor: flame sensor Description: HSI lights the main burner
Direct Spark Ignition(DSI)
Sensor: flame sensor Description: Spark lights the main burner
Standing Pilot
Sensors: Thermocouple 25-30 mv/Thermopile 750mv Description: Pilot is manually lit, pilot lights the main burner
Intermittent Pilot
Sensors: mercury switch, 3-wire bimetal, and flame sensor Description: Spark lights pilot, pilot lights the main burner
Which material would be best suited for use as a semi-conductor
Silicon
Thermocouple 30mvDC/ Thermopile750mvDC
Two dissimilar metals when heated produce mvDC
Any material that will readily release electrons is called
a Conductor
An ohmmeter should never be connected to
a live circuit
Flame sensor
a.A/C is sent from the ignition control board to sensor tip b.A/C is converted to DC through the path of the flame c.Circuit is completed through burner ground d.Back to the board.
In a series circuit, the voltage drop across each resistance (load) will do what
add up to equal the source voltage
How are fuses sized?
amps and volts
What is NOT a factor in determining impedance in an AC circuit
capacitive reactance
What is Current flow?
flow of electrons in the circuit.
An electric motor is considered what kind of load?
inductive load
The total resistance of a parallel circuit will be
less than the smallest resistance
When current flows, a _____________ is produced around the conductor
magnetic field
An electron has what kind of charge
negative charge
What is Impedance?
opposition to alternating current flow
In Ohms law what is Resistance
opposition to electrical flow.
In electrical wiring, a black colored wire usually indicates
the hot conductor
When resistors (loads) are wired in parallel
the voltage drop across each resistor (load) will be the same as the applied source voltage
The electric meter on a house measures the ___________ passing through it
wattage(KWH)
Three-wire bimetal
when bimetal is heated it warps causing contacts to switch position (cold to hot contacts)
Mercury Switch
when mercury is heated it expands causing contacts to switch position (cold to hot contacts)
