Study Refresher Flashcards
how is electrical PPE rated?
Hazard/Risk Category
how is arc rating measured
Calories/cm sq
how many levels of PPE are there for the Risk categories and what is the minimum PPE required for the levels of risk category?
1 = 4 cal/cm sq 2 = 8 cal/cm sq 3 = 25 cal/cm sq 4 = 40 cal/cm sq
name the 4 boundaries when working with exposed energized conductors or circuit parts
> arc flash boundary
limited approach boundary
Restricted approach boundary
Prohibited approach boundary
describe the arc flash boundary?
The boundary where an employee would be exposed to a curable 2nd degree burn
describe Limited Approach Boundary?
a shock protection boundary crossed by only qualified persons and not by an unqualified person unless escorted by a qualified person
Describe Restricted Approach Boundary
a shock protection boundary crossed by only qualified persons and because of its proximity to a shock hazard requires the use of shock protection techniques and equipment when crossed
describe Prohibited Approach Boundary
a distance from an exposed part which is considered the same as making contact with the live part
Describe an arc flash?
an undesired electrical discharge or explosion as a result of an arc fault that travels through the air between 2 conductors or a conductor and ground.
describe the live-dead-live test procedure?
- Wearing proper PPE, test your multi-meter on an energized circuit with similar voltage to that of the equipment that is about to be tested.
- Test the equipment circuit that is supposed to be de-energized
- Re-test the multi-meter on an energized circuit with similar voltage to insure the meter is still functioning properly
explain true Power and how it is measured
true power is power dissipated in a load and is measured in Watts
Explain Reactive Power and how it is measured
Reactive power is power that is absorbed and returned in load. It is Measured in Volts - Amps - Reactive (VARS)
Explain apparent power and how it is measured
apparent power is the total amount of power in a circuit, both dissipated and absorbed/returned. It is measured in Volts-Amps (VA)
what does VFD stand for?
Variable Frequency Drive
Describe the purpose of a VFD?
To control the speed and torque of an AC motor by varying the voltage and frequency supplied to that motor
Name the Primary components of a VFD
- A converter to convert the incoming AC voltage to DC voltage
- A filter to smooth out the DC voltage
- An inverter to convert the DC power into a simulated AC sine-wave that motor will accept
what does UPS stand for?
Uninterruptible Power Supply/source
Describe what a UPS is
It is the battery backup system that can supply emergency power to a load when the normal incoming power source is interrupted
name the 4 primary components of a UPS system and explain their purpose
- STATIC BYPASS (a circuit intended to bypass the UPS system and supply utility power to the load if there is a failure to the UPS)
- RECTIFIER (two main purposes. To convert incoming power from AC to DC voltage and keep the batteries in the UPS charged)
- BATTERIES (supply power to the load in the event of a loss of power from its normal source)
- INVERTER (converts the DC power from the UPS system back to a usable AC power to be supplied to the load)
what does STS stand for?
Static Transfer Switch
what does ATS stand for?
Automatic Transfer switch
describe what a STS does
It automatically transfers load for preferred power source to standby power source without interruption of server room load. Very fast switching with max delay of 5 msec.
Describe what a ATS does
Automatically transfers a power supply from its primary source to a backup source when it senses a failure or outage in the primary source.
what does BAS stand for?
Building Automation System
what does a BAS do?
Designed to automatically control building equipment to maintain environmental standards.
what does BTU stand for?
British Thermal Unit
in refrigeration what is a Ton?
a unit of power. lt is the power required to melt or freeze one short ton of ice per day at 32 degrees F
