Motor Control Flashcards
In which circuit are the pilot devices?
Control circuit.
What are two controller designations?
National electrical manufacturing association. And international electrotechinical commission.
What are the different setups for contractors?
Separate enclosures, combination starter, and an mcc.
Latter two via control txr
What are the required functions of motor control?
1) safety
2) starting
3) stopping
4) jogging or inching
5) speed control
6) reversing
7) surge protection
8) motor circuit protection via overloads.
What is nema’s range?
What about iec?
00 to 8 (which is 900hp)
A to z (which is 671.4 kw).
In a 2 wire, what kind of contact causes run? Also what are its characteristics?
A maintained contact causes it to run.
It has low voltage release, and auto restart.
What does low voltage release mean vs low voltage protection?
Low voltage release means there is only a release from load when there’s no power (ie when powers back, load turns on automatically).
Low voltage protection means it doesn’t turn on automatically.
How does a low voltage protection work in 3 wire control?
A momentary contact starts circuit. Power loss cuts the circuit.
What is a good way of seeing if a schematic symbol is normally open or closed?
Use gravity.
Limit sw symbol.
Triangular.
Pressure switch symbol.
Upside down D.
Do overload heating elements ever open?
No. They open ol contacts in controller.
Where to hook up alarm light to overload?
parallel to entire control cct through no ol contactsz.
All pilot devices require what?
Variable acting upon it.
How are M coil contacts linked to power circuit?
Via one armature movement. The 3 power contacts and the no contact and the nc contact of the m coil. All 5 adjoined via one armature movement.
Describe forward and reverse controller connections.
In forward controller, normal connections.
In reverse, bottom of c connects to bottom of reverse controller contact to the top of a (by top and below I mean above and below contacts of the forward controller).
How to get more contacts?
Add another relay aka aux contacts.
If there isn’t a control transformer stepping down voltage, then the coil must be…
Rated for line voltage.
In cold settings, which timer’s settings are changed? And which way?
Hydraulic. Time is extended. Oil
Moves slower.
Arrow up is TDOE or TDOD
Time to energize; on delay.