Features Of Maual Motors Flashcards
List two types of manual motor starters
Toggle switch, push switch
What does a toggle switch do
It is a snap on switch having a simple on and off switch.
It can be a single pole or double pole.
What is a push botton switch
Similar to a toggle switch except they use two different buttons to activate the contacts.
What is a drum switch
It is a rotary- action switch.
It’s normally used to control speed and change the direction of motors.
The moving contacts on the shaft are connected in series.
What is Melting alloy overload protection relays
Often called (solder pot relay) which is also a part in it containing a ratchet wheel and a set of normally closed electrical contacts.
It has a heater element and a contact witch are connected in series
What is a Bimetallic strip overload relay
The bimetallic stip is mechanically linked to a set of n.c electrical contacts. If sufficient heat is produced in the heater element the strip bends. Opening the line of contact to the motor
What does the melting alloy over load do when the current is high for a long period of time
And what is the other name for it
If the current is high for a long period of time the elements will heat up causing the alloy in the solder spot to liquefy.
Once the relay cools the solder will harden and the ratchet wheel can be reset to close the line contacts again
Low voltage contact = LVC
What is low voltage protection
If a machine has low voltage protection it means it will not restart if power is returned to it
What is lVP
Low voltage protection
If the motor has a
Three functions other than stopping and starting a motor controller l can provide
Running protection of the motor
Varies the speed of the motor
Automatic and remote control of the magnet
What is the fundamental difference between a magnetic connecter and a magnetic motor starter?
The magnetic motor starter consist of a magnet connecter plus overload, relay protection
What is the difference between the power circuit and the control circuit of motor
The power circuit = the main line contacts
The control circuit = electromagnetic, coil, and auxiliary contact
A three phase motor requires an overload ________ in series with each of the line conductors to the motor
Heater
Selection of the heater is based on the full load__________ of the motor, which is easily determined for the____________ of the motor
Current, nameplate
List four components found in a power circuit of an crossline, magnetic starter circuit
Disconnect switch
Fuse
Power contacts
Heater elements
List three components found in the control circuit of a magnetic starter
Two positions selector switches
Motor coil
Auxiliary contact
A two wire control circuit provides under voltage____________
Release
At three wire control circuit provides under voltage____________
Protection
Two wire control circuits usually include___________ Contacts initiating devices
Maintained
What is the purpose of a pilot light?
It’s used to turn on a motor in a remote location
When operating a motor from two or more locations the stop buttons are connected in___________ and the buttons are connected in___________
Serious
Parallel
What is meant by full voltage control
It is when the pilot device is in the control circuit operating at the same voltage as the motor or power supply
How does a wiring diagram defer from a schematic diagram?
Schematic diagram, uses symbols and interconnecting lines
wiring diagram shows where the wires are connected and where they are located
What is a wire numbering system?
It is a numeric marking method, applied to schematic diagrams to help identify conductor terminations
Why are numbering systems helpful?
They are interconnected with the conductors
Eg the numbers go to the numbers 2-2 3-3 and so on
Why is it sometimes necessary to use? Control relays in conjunction with magnetic motor starters
If a magnetic starter does not have enough auxiliary control for the control circuit operation then one or more control relays are used
When I normally open contact on a control relay is rated at 10 A AC. Does that mean it could break and break all values of current up to and including 10
It means that it has a continuous value of 10A
What is a latching relay?
A latching relay is a relay that when energized the coil and relay remain mechanically latched in the closed position
What is meant by the term jogging
Jogging is a quickly repeated closure of a circuit. It starts a motor from rest and causes small movements of the motor driven machine.
What hazard can occur when using only a simple jog button with a stop and start circuit
The motor may continue to run if the jog button closes before the seal in contact has a chance to open
What do you do if your jog button with a stop start switch creates a hazard
Are using a definite break device, such as a selector switch, or a control relay in the jog control, seal in circuit
