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

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 1 LB 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 volt meter + NO 0 current meter A normally open push button. Inductor with a ferromagnetic core light bulb with an incandescent filament

Relay review 0 volt meter + NO 0 current meter 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 volt meter + NO 0 current meter NO + 0 current meter

Relay review 0 volt meter + NO + 0 current meter NO 0 current meter

Relay review 0 volt meter + NO + 0 current meter NO 0 current meter

Relay review 0 volt meter + NO + 0 current meter 0 current meter NO

Circuit ladder Diagram Cartoon of circuit Ladder diagram of circuit 0 voltage

Circuit ladder Diagram Cartoon of circuit Ladder diagram of circuit 0 voltage PB 1 LB 1

Circuit ladder Diagram Cartoon of circuit Ladder diagram of circuit 0 voltage PB 1 LB 1 LB2 LB1 = light bulb #1 LB2 = light bulb #2 PB1 = push button #1 MR1= Motor contacts #1 M1 = Meter #1 M2 = Meter #2 MR 1 M1 MR 1 M1 M2

Circuit ladder Diagram 0 voltage + NO 0 Current + 0 current NO relay Cartoon of circuit Ladder diagram of circuit 0 voltage PB 1 LB 1 MR 1 M1 M2 LB2 LB1 = light bulb #1 LB2 = light bulb #2 PB1 = push button #1 MR1= Motor contacts #1 M1 = Meter #1 M2 = Meter #2

Circuit ladder Diagram Cartoon of circuit Ladder diagram of circuit 0 voltage PB 1 LB 1 MR 1 M1 LB1 = light bulb #1 LB2 = light bulb #2 PB1 = push button #1 MR1= Motor contacts #1 M1 = Meter #1 M2 = Meter #2

+ 0 volt meter NO 0 current meter NO Relay with N.O. auxiliary contacts

+ 0 volt meter NO 0 current meter NO

+ Relay with N.O. auxiliary contacts 0 volt meter NO 0 current meter NO This relay circuit is now energized.

+ 0 volt meter NO 0 current meter NO Relay with N.O. auxiliary contacts This relay circuit is de-energized.

Relay with N.O. auxiliary contacts Cartoon of circuit Ladder diagram of circuit NO + 0 voltage NO 0 current 0 voltage PB 1 LB 1 MR 1 M1 PB 1 LB 1 MR 1 M1

Relay with N.O. auxiliary contacts Cartoon of circuit Ladder diagram of circuit NO + 0 voltage NO 0 current 0 voltage PB 1 LB 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 NO + 0 voltage NO 0 current 0 voltage PB 1 LB 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 NO + 0 voltage NO 0 current 0 voltage PB 1 LB 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 NO + 0 voltage NO 0 current 0 voltage PB 1 LB 1 MR 1 M1 PB 1 LB 1 MR 1 M1 CR 1

Relay with N.O. auxiliary contacts Cartoon of circuit Ladder diagram of circuit NO + 0 voltage NO 0 current 0 voltage PB 1 LB 1 MR 1 M1 PB 1 LB 1 MR 1 M1 CR 1 Motor circuit is energized.

Relay with N.O. auxiliary contacts Cartoon of circuit Ladder diagram of circuit NO + 0 voltage NO 0 current 0 voltage PB 1 LB 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 volt meter + NO NC 0 current meter Relay with N.C. auxiliary contacts This relay circuit is now de-energized. This relay circuit is now energized.

0 volt meter + NO This relay circuit is now energized. This relay circuit is now de- energized. 0 current meter NONC Relay with N.C. auxiliary contacts

This relay circuit is now de-energized. This relay circuit is now energized. 0 volt meter + NO 0 current meter 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 1 LB 1 MR 1 M1 CR 1 PB 1 LB 1 MR 1 CR 1 NO

0 voltage + NO 0 current NC Relay with N.C. auxiliary contacts Cartoon of circuit Ladder diagram of circuit 0 voltage PB 1 LB 1 MR 1 M1 CR 1 PB 1 LB 1 MR 1 CR 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 0 current NC Relay with N.C. auxiliary contacts Cartoon of circuit Ladder diagram of circuit 0 voltage PB 1 LB 1 MR 1 M1 CR 1 PB 1 LB 1 MR 1 CR 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 0 current NC Relay with N.C. auxiliary contacts Cartoon of circuit Ladder diagram of circuit 0 voltage PB 1 LB 1 MR 1 M1 CR 1 PB 1 LB 1 MR 1 CR 1 This oscillation of the CR1 and MR 1 contacts continues as long as PB 1 is passive.

0 voltage + NO 0 current NC Relay with N.C. auxiliary contacts Cartoon of circuit Ladder diagram of circuit 0 voltage PB 1 LB 1 MR 1 M1 CR 1 PB 1 LB 1 MR 1 CR 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 0 current NC Relay with N.C. auxiliary contacts Cartoon of circuit Ladder diagram of circuit 0 voltage PB 1 LB 1 MR 1 M1 CR 1 PB 1 LB 1 MR 1 CR 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 1 LB 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 1 LB 1 MR 1 M1 CR 1 x

End of Presentation