Appliances motors controllers & test equipment Flashcards
Are most standard household appliances rated less than 12 amps?
Yes
So they can be used in standard outlets on a 110 volt, 15 amp circuit
What device usually serves as the disconnecting method for fixed or stationary appliances that are not rated at 300 voltsamperes or 1/8 horsepower ?
Branch circuit over current device
What device usually serves as the the disconnecting method for fixed or stationary appliances that are rated at greater than 300 voltsamperes or 1/8 horsepower ?
A circuit breaker if it is in sight of the appliance or is capable of being locked in an open position
What device usually serves as the disconnecting method for portable appliances ?
An attachment plug and receptacle
What is an appliance branch circuit
Ant circuit which supplies electrical energy to one or more outlets to which appliances are connected
What is the minimum number of appliance receptacle branch circuits that must be installed in a kitchen for receptacle outlets ?
At least 2
What is the normal circuit required for a washing machine ?
120volts
60cycle
15 to 20 amp circuit
What are the three basic types of appliances
Fixed
Portable
Stationary
What is the correct reading for a good wire when using an ohmmeter for testing wire ?
0 ohms
What is the correct reading for a faulty wire when using an ohmmeter for testing wire ?
Infinity
What is the probable cause of an oven that is too hot ?
An inoperative oven control or the wrong element
What are probable causes of no heat at a single surface burner ?
- Burned out element
- An open in the burner circuit
- Corroded contacts in a control switch
- Loose terminal connections at the burner unit
What is the remedy for appliances that fail to heat when plugged into the appliance outlets on an eke true range ?
Cleaning and tightening of the connections ; replacement of fuses, wires, or outlets if required
What is the probable cause of uneven baking ?
A tilted range or oven racks which are not positioned on the proper support
What are the two classes of appliance controls ?
Manual and automatic
What are the principal types of manual appliances controls?
Toggle switches and rotary switches
Is it generally true that new toggle switches are so inexpensive that it is more economical to replace old ones rather than repair them ?
Yes
What type of switches are normally used to control the top elements of electrical ranges ?
Rotary switches
What type of switch is used in commercial ranges and in galley installations ?
A pull turn switch
What is the basic function of an appliance automatic control ?
To turn a current on and off as required in order to maintain a desired temperature
What type of automatic control consists of a control switch that Is operated by the expanding and contracting effect caused by two pieces of dissimilar metals welded together ?
The bimetallic blade control switch
What is the repair of a bimetallic blade control switch limited to?
To adjustment of the temperature setting
What type of control is operated by thermostatic metal that coils and uncoils when heat is applied, thus regulating a switch in order to make and break an electric circuit ?
A helix control switch
Which type of control is the most commonly used control for automatic regulations of temperature of cooking appliances ?
A hydraulic control
What is the normal setting for the safety device of an appliance hydraulic control that trips upon reaching the set temperature ?
450 degrees F
What do repairs to a hydraulic control consist of ?
Adjustment of the temperature setting
What is the purpose of an appliance timer ?
To automatically control an appliance circuit or to provide a warning that predetermined amount of time has elapsed
What is the first step in troubleshooting an appliance circuit ?
Study the schematics
What is the second step in trouble shooting an appliance circuit ?
Visually inspect the circuit
What does a visual check consist of ?
Checking for any loose wiring , loose connections , burnt wires , and or burnt components
What is the first part of an appliance circuit such must be checked when attempting to locate an electrical fault in an appliance ?
The power supply and condition of the powers cord
Should all circuits be regarded as live ?
Yes until all switches have been opened or the required voltage tests have been performed that indicate a dead circuit
Why must all switches be locked and tagged in the open position when working on a circuit ?
To keep other personnel from tampering and creating a hazardous condition
What should an ohmmeter read if a switch is on ?
Zero
What does a portable electrical tool tester consist of ?
A transformer , sensing relays , indicator lights , an audible warning buzzer and suitable leads for tool or appliance connections
How many amps are passed through a tool tester ?
About 30 amps
Which light glows glows on a tool tester if there is no equipment ground ?
The open equipment ground light
What relay is activated in a tool tester if the resistance of the ground on the equipment being tested is approximately 0.2 to 1.5 ohms?
The faulty equipment ground sensing relay
What causes the presence of a dangerous power ground to occur when using a tool tester ?
Carbon, moisture paths , or or deterioration of insulation
What is a current meter ?
Any meter used to measure the flow of electric current
What is an ammeter ?
A current meter that measures current amperes
Is an ammeter connected in series with the circuit source and load ?
Yes
Where can portable ammeters be temporarily connected into a wiring system ?
At any point in the system where a current reading is needed
Do all mannered have an adjustable scale ?
Yes the function and range of the ammeter are altered as the scale is changed
What scale should be selected on a clamp on ammeter when taking a measurement of an unknown amount of current ?
The highest amperage range should be used
What is the actual meter component of a voltmeter ?
A milliammeter or a micrometer
What do portable voltmeters measure ?
One or more ranges of voltage
What is the purpose of a range selector switch on a voltmeter ?
To internally connect the appropriate multimeter resistor into the meter circuit for the correct range of voltage to be measured
