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GTHS KUMBO_Electrical Department_Mock exam......March.2012 1

I. NUMERATION SYSTEMS

Let us consider the following numbers:

)2(110101101A )8(624B )16(71AC

1. Convert A into octal and hexadecimal.

2. Convert B and C into binary.

3. Calculate:

)2()2()2( BAX ; )16()16()16( CAY )8()8()8( BAW

II. COMBINATORIAL LOGIC

1. Let us consider the logic equation:

cbabcacbaabcS .

a. Simplify S algebraically.

b. Establish the logic diagram of the simplified expression of S.

2. Let us now consider the logic equation:

zyxyzxxyF

a. Complete the truth table of F.b. Establish the Karnaugh map of F.

c. Extract the simplified expression of F from this map.

d. Draw the electric diagram of F.

3. Consider a logic function described by the Karnaugh map below:

a. Establish the truth table of X

b. From the Karnaugh map, determine the simplified expression of X.

c. Draw the logigram of X.

REPUBLIC OF CAMEROONPeace Work Fatherland

GTHS KUMBO/ ELECT DPT

MOCK EXAMINATIONS

Class: CI6

Option: IH (Clothing Industry)

Duration: 02H

Coefficient: 2

Written paper

AUTOMATION

No document is allowed except the one given tothe candidates b the examiners.

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III. SEQUENTIAL LOGIC

1. Description

The device enables to close bottles containing products of textile industry. The

bottles to close are transferred under the mechanism thanks to a rolling carpet.

During their motion, the bottles are maintained by support.

2. Functioning

When the system detects a bottle at the level of corking, and if there is a cover in the

mouth and an action on the start push button will lead to:

Downward motion of corking unit;

Pressing of the cover;

Forward motion of the carpet by one step;

End of cycle.

There is a possibility for the operator to select either the cycle by cycle or the

automatic working by switching the SA/SC switch on the suitable position.

Initial conditions:

All the cylinders are returned;

The carpet is stopped.

X

AB

CD

00 01 11 10

00 1 0 0 1

01 1 1 1 1

11 1 0 1 0

10 1 0 0 1

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3. GRAFCET viewed from the system part.

Initial conditions and start cycle andbottles detected and cover available

Downward motion of the corking unit

Unit at the lower position

Pressing of the cover on the bottle

Cover pressed

Rolling of the carpet by one step

One step obtained and automaticmode selected and bottle present

One step

obtained andcycle by cycle mode

0

1

2

3

4. Technological specificationsActuators

The system is equipped with:

Two pneumatic double acting cylinders 1C and 2C controlled by solenoids piloted

distributors.

Sensors

1S0, 1S1, 2S0, 2S1 are limit switches for the cylinders. Sp and Sb detect a bottle and

a cover respectively.

SA/SC is the cycle bicycle/automatic switch.

SM is the start push button.

DESIGNATION AND FUNCTIONS OF ACTUATORS, PRE ACTUATORS AND

SENSORS.

FUNCTION ACTUATOR PREACTUATOR SENSOR

Downward/upward motion of corking unit 1C 1D 1S0, 1S1

Cover pressing 2C 2D 2S0, 2S1

Rotation of carpet M KM

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5. Work required

4. Give the action associated to stage 3.

5. Give the activating condition of stage 1.

6. Represent a 5/2 solenoid piloted control distributor by its normalised symbol.

7. Name a pre-actuator that can control the cylinder 2C.

8. Draw the Grafcet viewed from the control part of the system.

9. Complete the table of activation and deactivation of stages of this Grafcet.

Stage Activation deactivation

SUBJECT MASTER: NGOUNE Jean-Paul,

PLET Electrotechnics, GTHS KUMBO.