Seal-in is not a hotel in Monterey This presentation is partially animated. Only use the control...

Seal-in is not a hotel in Monterey

This presentation is partially animated. Only use the control panel at the bottom of screen to review what you have already seen. When using your mouse, make sure you click only when it is within the blue frame that surrounds each slide.

Your comfort level with your responses to the following 2 question assessment tool should indicate if the presentation that follows will increase you knowledge base on the topic outlined by the questions in this tool.

Pre-presentation Self Assessment Activity

Pre-presentation Self Assessment Activity

2) The following diagram indicates that the relay circuit controlled by MR1 is energized after the pushbutton has been pushed and then released.

yes

no

PB 1LB 1 MR 1 M1

CR 1

1) Draw a ladder circuit diagram that will show the wiring of a normally open push button such that pushing the button will seal in a motor relay contact set, MR1.

Auxiliary contacts for

seal in circuits

Relay review

0

voltmeter

+

NO

0

currentmeter

A normally open push button.

Inductor with a ferromagnetic core

light bulb with an incandescent filament

Relay review

0

voltmeter

+

NO

0

currentmeter

Magnetic field lines indicate presence of a magnetic field

When current flows a magnetic field is generated around the flowing electrons.

Note:(a) This magnetic field is also called an electromagnetic field. (b) However, this magnetic field is the same magnetic field as the field made by two bar or a single horse shoe magnet

Relay review

0

voltmeter

+

NO

0

currentmeter

NO

+

0

currentmeter

Relay review

0

voltmeter

+

NO

+

0

currentmeter

NO0

currentmeter

Relay review

0

voltmeter

+

NO

+

0

currentmeter

NO0

currentmeter

Relay review

0

voltmeter

+

NO

+

0

currentmeter

0

currentmeter

NO

Circuit ladder Diagram

0

voltage

+

NO

0

Current

+

0

current

NO

relayCartoon of circuit

Ladder diagram of circuit

0

voltage

Circuit ladder Diagram

0

voltage

+

NO

0

Current

+

0

current

NO

relayCartoon of circuit

Ladder diagram of circuit

0

voltage

PB 1

PB 1

LB 1

LB 1

Circuit ladder Diagram

0

voltage

+

NO

0

Current

+

0

current

NO

relayCartoon of circuit

Ladder diagram of circuit

0

voltage

PB 1

PB 1

LB 1

LB 1 LB2

LB1 = light bulb #1LB2 = light bulb #2PB1 = push button #1MR1= Motor contacts #1M1 = Meter #1M2 = Meter #2

MR 1 M1

MR 1

M1M2

Circuit ladder Diagram

0

voltage

+

NO

0

Current

+

0

current

NO

relayCartoon of circuit

Ladder diagram of circuit

0

voltage

PB 1

PB 1

LB 1

LB 1

MR 1

MR 1

M1

M1M2

LB2

LB1 = light bulb #1LB2 = light bulb #2PB1 = push button #1MR1= Motor contacts #1M1 = Meter #1M2 = Meter #2

Circuit ladder Diagram

0

voltage

+

NO

0

Current

+

0

current

NO

relayCartoon of circuit

Ladder diagram of circuit

0

voltage

PB 1

PB 1

LB 1

LB 1

MR 1

MR 1

M1

M1

LB1 = light bulb #1LB2 = light bulb #2PB1 = push button #1MR1= Motor contacts #1M1 = Meter #1M2 = Meter #2

+

0

voltmeter

NO

NO0

currentmeter

NO

Relay with N.O. auxiliary contacts

+

Relay with N.O. auxiliary contacts

0

voltmeter

NO

0

currentmeter

NO NO

+

Relay with N.O. auxiliary contacts

0

voltmeter

NO

0

currentmeter

NO NO

This relay circuit is now energized.

This relay circuit is now energized.

+

0

voltmeter

NO

NO0

currentmeter

NO

Relay with N.O. auxiliary contacts

This relay circuit is de-energized.

This relay circuit is de-energized.

Relay with N.O. auxiliary contacts

Cartoon of circuit

Ladder diagram of circuit

NONO

+

0

voltage

NO

0

current

0

voltage

PB 1LB 1 MR 1 M1

PB 1

LB 1

MR 1

M1

Relay with N.O. auxiliary contacts

Cartoon of circuit

Ladder diagram of circuit

NONO

+

0

voltage

NO

0

current

0

voltage

PB 1LB 1 MR 1 M1

PB 1

LB 1

MR 1

M1

CR 1

LB2CR 1

LB2

Relay with N.O. auxiliary contacts

Cartoon of circuit

Ladder diagram of circuit

NONO

+

0

voltage

NO

0

current

0

voltage

PB 1LB 1 MR 1 M1

PB 1

LB 1

MR 1

M1

CR 1

LB2CR 1

LB2

Motor circuit is energized.

Relay with N.O. auxiliary contacts

Cartoon of circuit

Ladder diagram of circuit

NONO

+

0

voltage

NO

0

current

0

voltage

PB 1LB 1 MR 1 M1

PB 1

LB 1

MR 1

M1

CR 1

LB2CR 1

LB2

Motor circuit stays energized.

Relay with N.O. auxiliary contacts

Cartoon of circuit

Ladder diagram of circuit

NONO

+

0

voltage

NO

0

current

0

voltage

PB 1LB 1 MR 1 M1

PB 1

LB 1

MR 1

M1

CR 1

CR 1

Relay with N.O. auxiliary contacts

Cartoon of circuit

Ladder diagram of circuit

NONO

+

0

voltage

NO

0

current

0

voltage

PB 1LB 1 MR 1 M1

PB 1

LB 1

MR 1

M1

CR 1

CR 1

Motor circuit is energized.

Relay with N.O. auxiliary contacts

Cartoon of circuit

Ladder diagram of circuit

NONO

+

0

voltage

NO

0

current

0

voltage

PB 1LB 1 MR 1 M1

PB 1

LB 1

MR 1

M1

CR 1

Motor circuit stays energized.

Push button is disengaged.

Ladder diagram still shows a continuous path from the left to right through the relay. The motor

relay circuit has been “sealed in”.

CR 1

0

voltmeter

+

NO

NONC0

currentmeter

Relay with N.C. auxiliary contacts

This relay circuit is now de-energized.

This relay circuit is now energized.

0

voltmeter

+

NO

This relay circuit is now energized.

This relay circuit is now de-energized.

0

currentmeter

NONC

Relay with N.C. auxiliary contacts

This relay circuit is now de-energized.

This relay circuit is now energized.

0

voltmeter

+

NO

0

currentmeter

NONC

Relay with N.C. auxiliary contacts

0

voltage

+

NO

0

current

NC

Relay with N.C. auxiliary contacts

Cartoon of circuit

Ladder diagram of circuit

0

voltage

PB 1LB 1 MR 1 M1

CR 1

PB 1

LB 1

MR 1CR 1

NO

0

voltage

+

NO

NO0

current

NC

Relay with N.C. auxiliary contacts

Cartoon of circuit

Ladder diagram of circuit

0

voltage

PB 1LB 1 MR 1 M1

CR 1

PB 1

LB 1

MR 1CR 1

However, since the coil is energized, the CR 1 contacts are forced out of their normal position. They immediately open and cause an open circuit that de-energizes the coil.

0

voltage

+

NO

NO0

current

NC

Relay with N.C. auxiliary contacts

Cartoon of circuit

Ladder diagram of circuit

0

voltage

PB 1LB 1 MR 1 M1

CR 1

PB 1

LB 1

MR 1CR 1

Now the CR1 contacts return to their normal position, the coil is re-energized and then the CR 1 contacts are again forced out of their normal position.

0

voltage

+

NO

NO0

current

NC

Relay with N.C. auxiliary contacts

Cartoon of circuit

Ladder diagram of circuit

0

voltage

PB 1LB 1 MR 1 M1

CR 1

PB 1

LB 1

MR 1CR 1

This oscillation of the CR1 and MR 1 contacts continues as long as PB 1 is passive.

0

voltage

+

NO

NO0

current

NC

Relay with N.C. auxiliary contacts

Cartoon of circuit

Ladder diagram of circuit

0

voltage

PB 1LB 1 MR 1 M1

CR 1

PB 1

LB 1

MR 1CR 1

This immediately causes the CR 1 contacts to return to their normal position and re-energize the coil. This cycling (oscillation) continues until the CR 1 contacts burn out.

0

voltage

+

NO

NO0

current

NC

Relay with N.C. auxiliary contacts

Cartoon of circuit

Ladder diagram of circuit

0

voltage

PB 1LB 1 MR 1 M1

CR 1

PB 1

LB 1

MR 1CR 1

The same oscillation behavior will happen in this circuit arrangement when PB 1 is or is not engaged.

Pre-presentation Self Assessment Activity

2) The following diagram indicates that the relay circuit controlled by MR1 is energized after the pushbutton has been pushed and then released.

yes

no

PB 1LB 1 MR 1 M1

CR 1

1) Draw a ladder circuit diagram that will show the wiring of a normally open push button such that pushing the button will seal in a motor relay contact set, MR1.

PB 1LB 1 MR 1 M1

CR 1

x

End of Presentation