Solid-State Devices Used in Industrial Logic Circuits: QUIZ

TRUE OR FALSE

1. ______ The start switches LSI and LS2 in this figure are connected to form OR logic, since any of the three switches can turn on the control relay CR1.

2. _______ A relay with normally closed contacts will provide logic function that's similar to a NOT logic gate.

3. _______ An optoelectronic circuit like the one shown in this figure can provide isolation between two circuits.

4. _______ A solid-state relay can provide both the function of isolation and amplification.

5. _______ One advantage relays have over solid-state logic devices is that relays are faster acting.

MULTIPLE CHOICE

1. A typical relay has _______

a. one coil and one or more sets of contacts.

b. one set of contacts and one or more coils.

c. multiple coils and multiple sets of contacts.

2. A solid-state relay uses _______ to switch power.

a. a coil and electromechanical contacts

b. a light-emitting diode (LED) and phototransistor

c. a rectifier diode and a relay coil

3. The Bin #1 Fill solenoid in line 7 of this ladder-logic diagram will be energized when CR1 is energized and ______.

a. prox I is high and prox 2 is low.

h. prox 2 is high and prox I is low.

c. prox 1 is high and prox 3 is low.

4. The alarm horn in line 10 of this ladder-logic diagram will be activated when ______

a. CR2 and CR1 are both energized for more than 2 minutes.

b. either CR2 or CR4 are energized for more than 2 minutes.

c. either CR2 or CR4 are dc-energized for more than 2 minutes.

5. The Thunderbird program logic in this figure will be selected when ______

a. prox 1 is high and prox 2 and prox 3 are low.

b. prox 1 is low and prox 2 and prox 3 are high.

c. prox 2 is high and prox I and prox 3 are low.

PROBLEMS

1. Draw the symbol for and explain the operation of the basic logic gates: AND, OR, NOT, NAND, and NOR.

2. Draw or sketch the locations where you would place voltmeter leads in order to test the relay logic in this figure if the fill solenoid would not energize.

3. Draw or sketch a circuit that's used for signal conditioning or amplifying an output signal from a logic gate to make the signal interface a 110 volts ac relay coil.

4. Draw or sketch the relay contacts used to create the following gates: AND, OR, NOT, NAND, and NOR.

5. Draw a truth table for the operation of the bin level control circuits shown in this figure.