Ch 7 Solenoids

Electromagnet

A _____ is magnet whose magnetic energy is produced by the flow of electric current

Iron

An electromagnet consists of a ______ core inserted into a coil

North

The left handed rule states that if the fingers of the left hand are wrapped in the direction of the current flow of the coil, the thumb points to the magnetic ____ pole of the coil

Electric Current

An electromagnet's strength can be controlled by regulating its _____

Directly

The strength of a magnetic field and current are ____ related

Armature

A ____ is the movable part of a solenoid

Five

There are _____ different solenoid configurations

Bell-Crank

A ______ solenoid uses a lever attached to an armature to transform the armature's vertical action into a horizontal action

Eddy

_____ current is unwanted current induced i the metal structure of a device due to the rate of change in the induced magnetic field

Shading

A _____ coil sets up an auxiliary magnetic field that helps hold in the armature as the main coil magnetic field drops to zero in an AC circuit

Solenoid

A _____ is an electric output device that coverts electrical energy into a linear mechanical force

Shading coil

A ____ is a single turn of conducting material (normally copper or aluminum) mounted on the face of the magnetic laminate assembly or armature of a solenoid

Copper

Magnetic coils are normally constructed of many turns of insulated _____ wire wound on a spool.

6 to 10

In a solenoid coil, the inrush current is approximately ____ times the sealed current

Inductive

The magnetic opposition upon energizing a solenoid is referred to as ____ reactance or total impedance.

volt amperes

Magnetic coil data is normally given in ____

Pick-up

____ voltage is the minimum voltage that causes the armature to start the move

80% to 85%

For most solenoids, the minimum pick-up voltage is about _____ of the solenoid rated voltage.

70

Drop-out voltage can be as low as ____% of the solenoid rated voltage

Voltage

____ variations are one of the most common causes of solenoid failure

Duty cycle

A solenoid's ____ is usually given in operations per minute

A seal-in

____ voltage is the minimum control voltage required to cause the armature to seal against the pole faces of the magnet

Manufacturer charts

_____ are used to help determine the cause of solenoid failure

10

The voltage applied to a solenoid should be +_____% of the solenoid rated value

Snubber

A ____ circuit is a circuit that suppresses noise and high voltage on the power lines

overheats

A solenoid ______ when the voltage is excessive

Several times its rated

A solenoid draws _____ current when first connected to power

mechanical damage

Solenoids usually fail due to electrical problems or _____