Reversing Motors Flashcards
What is the industry standard for reversing a 3 phase motor
Interchange L1 and L3
How do you reverse the rotation of a single phase motor
By interchanging the leads of the starting or running windings
How do you reverse the rotation of DC series shunt and compound motors
By reversing the direction of current through the field without changing the direction of current through the armature or vice versa
What is a drum switch
A manual switch made up of moving contacts mounted on an insulated rotating shaft
The industry standard is to reverse the direction of current through the____
Armature
What is the only difference between manual and magnetic reversing starters
The addition of forward and reverse coils and the use of Auxiliary contacts
The power circuit includes…
The incoming circuit main power, the motor starter, and the motor.
The control circuit includes…
The required circuit inputs, motor starter coils, motor starter auxiliary contacts, overload contacts, timers, counters, and any other device designed to operate in the control circuit.
List the 4 basic methods of motor control
Direct hard wiring, hard wiring using terminal strips, PLC wiring, and electric motor drive wiring
Which is the oldest and most straight forward motor control wiring?
Direct hard wiring
What is the disadvantage of direct hard wiring?
Troubleshooting and circuit modification are time consuming
____is a method of motor braking in which motor connections are reversed so that the motor develops countertoque that acts as a braking force.
Plugging
List 4 types of motor braking
- Friction Brakes
- Plugging
- Electric braking
- Dynamic Braking
_____is a method of braking on which a dC voltage is applied to the stationary windings of a motor after the AC voltage is removed.
Electric Braking
A motor cannot be used for _____ if it cannot be reversed at full speed.
Plugging
High current and high heat result from_____ a motor to stop.
Plugging
List two advantages of friction brakes
- Low initial cost
2. simplified maintenance (but require more maintenance than other braking methods)
_____ is a method of motor braking in which a motor is reconnected to act as a generator immediately after it is turned off.
Dynamic Braking
_____braking is usually applied to DC motors.
Dynamic
_____ are often used along with dynamic braking in applications that require the load to be held.
Electromechanical friction brakes
A ____ is a switching device that has no contacts and switches entirely my electronic means.
Solid State Relay
Three advantages of solid state electronics
- Declining cost
- High reliability
- immense capability
Three parts of an SSR circuit
- input circuit
- control circuit
- output (load switching) circuit
The ____ is the part of an SSR that determines when the output component is energized or deenergized.
Control circuit
SSRs can be connected in series or parallel
True or False
True
A________ is an SSR that turns on the load when the control voltage is applied and the voltage at the load crosses zero.
Zero Switching Relay
The _____ is the most widely used relay.
Zero switching Relay
A_______ relay is an SSR that turns on the load immediately when the control voltage is present.
Instant On Switching Relay
_____ relays are designed to control inductive loads.
Instant-on
List 4 SSR switching methods
1.Zero Switching
2.Instant On
3.Peak
4 .Analog
A _____switching relay is an SSR that turns on the load when the control voltage is present and the voltage ar the load is at its peak.
Peak
An ____ switching relay is an SSR that has an infinite number of possible output voltages within the rated range of the relay.
Analog
____switching allows for a ramp-up function of the load.
Analog
____ switching relays are designed for closed loop applications.
Analog
The performance of an SSR is affected by_____.
Ambient temperature
_____is a method of motor braking in which the regenerated power of a DC motor is returned to the input power supply.
Regenerative braking
Motor speed is controlled by controlling the ____ to a DC motor.
Voltage
