Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
30 Cards in this Set
- Front
- Back
|
Reversing the direction of a induction motor is done by reversing the the stators magnetic field. How is this done electrically? |
Interchanging any 2 of the supply power to the stator |
|
|
How many contactors does a reversing motor starter have? |
2 |
|
|
How many overload relays are needed for a reversing motor starter that has 1 motor ? |
1 |
|
|
What are the 2 types of interlocks in a motor control circuit? |
Mechanical and electrical |
|
|
What will happen to the coil if there is mechanical interlock and both start and stop push buttons are pressed at the same time? |
Coil will burn out |
|
|
What are the electrical interlocks labeled for iec and nema? |
IEC it is 21 and 22 NEMA is 6 and 7 |
|
|
If a motor is repeatedly energized in short bursts of rated voltage this is called? |
Jogging |
|
|
If a motor is started ar reduced voltage to let the machine creep to a desired location this is called? |
Inching |
|
|
What are the 3 most often used devices to open and close a circuit? |
1.pushbutton contacts 2.selector switches 3.relay contacts |
|
|
A connection method that prevents the motor from accidentally going into run if the button is released to quickly. |
Positive jogging |
|
|
What can the starting current of a 3 phase iduction motor be? |
2 to 8 times full load current |
|
|
The size of mottor starter for jogging must be what size? |
1 size larger than continuous duty starters |
|
|
What must the rating be of an IEC starter that is used for jogging ? |
AC-4 |
|
|
What does the hand position do on a selector switch for a motor control circuit? |
Means the motor is running |
|
|
When a control switch is in auto what does it do? |
Motor is contolled by an automatic control device |
|
|
Another name for an interconnection diagram? |
Pin-out |
|
|
What are the 3 comonents of a control system? |
Inputs, outputs, controller |
|
|
What are the 3 basic types of timing devices ? |
1.spring wound interval timers 2.mechanical and electronic time switchs 3.timing relays |
|
|
What are some over and above timing contact functions? |
Interval timing, one shot, repeat cycle. |
|
|
What is it called when you interchange the supply to two of the stator phase windings? |
Plugging |
|
|
When a motor is reversed quickly in the other direction? |
Plugging |
|
|
What prevents the motor from turning in the opposite direction until the motor comes near or a complete stop. |
Anti plugging |
|
|
Is anti plugging normally open or normally closed switch? |
Normally closed |
|
|
What is a single phase mutual control transformer used for? |
Reduce the line voltage to a lower, safer value |
|
|
Control transformer range in size capacity of what VA? |
25 to 5000 VA |
|
|
What are the 3 styles of control transformers ? |
1.outdoor enclosed 2.indoor open 3.indoor enclosed |
|
|
List 3 ways of controlling the timing of a timing relay? |
1.electronic 2.pneumatique 3.fluid filled dashpot |
|
|
What are the 2 main purposes of a control transformer ? |
1.reduce shock hazard 2.isolate the power and control circuit |
|
|
CPU of a PCL is to read inputs, exécute the program and wright to the outputs. This process is know as? |
Processor scan |
|
|
What are the 2 most common analog signals used in a PLC? |
0 to 10 volts DC and 4 to 20 milli amps |
