Elec Flashcards
What are the voltage ratings and colour codes for rubber gloves from class 00 to 2
- class 00: 500V Beige
- class 0: 1000V Red
- class 1: 7500V White
- class 2: 17000V Yellow
What are the 5 emergency procedures after an electrical shock?
- Remove the victim
- Prevent further injury
- Send for help
- Eliminate the danger
- Report the incident
What are ammeters?
Inserted in series in a circuit to measure current.
What range of voltages and currents refrigeration mechanics work with?
5 VDC - 600 VAC, 20 mA - several hundred Amps
How is ampere expressed as in relation to coulomb
I=Q/t
What’s the process of producing EMF by adding heat to 2 dissimilar metals
Seebeck Effect
What are thermocouples
Thermoelectric generators that change heat into EMF
What are the 6 sources of emf?
Magnetic
Chemical
Friction
Heat
Pressure
Light
What current can cause involuntary muscle loss?
> 15mA
What are the four factors that affect current on the human body
-Area of contact
-Pressure
-Skin resistance
-Point of contact
What are megohmmeters?
Used to test electrical insulation resistance by applying a high voltage (>10 kV) typically at 500 VDC with minimum IR of 1 MO
What is Kirchoff’s Current Law?
Total current or charge entering a junction is equal to the charge leaving the junction:
I (exiting) + I (entering)=0
What is Kirchhoff’s Voltage law
The sum of all voltage drops in a series circuit equals the total applied voltage
E = V¹ + V² + Vn
Phi Φ
Magnetic flux
Residual magnetism
Ability for a material to remain magnetic after the magnetic force has been removed
Retentivity
Ability for a material to retain magnetic qualities after the magnetic force has been removed
Factors effecting amount of EMF generated from a generator
Amount of magnetic flux, the speed of cutting the lines of force, and length of conductor (number of coiling)
In a capacitance circuit, power is consumed by
Reactive power
In an inductive circuit, power is consumed by
Apparent power
What’s the unit for reactive power
Voltamp reactive, VAR
What’s the unit for apparent power
Voltamps, VA
What’s the unit for capacitance
Farad, F
What’s the unit for inductance
Henry, H
What physical properties determines capacitance
Size of capacitor (dielectric material, size of electrode plates and the distance between them)
