Question

Electrical Knowledge:

1. Know what a multimeter is and how to use it.

2. Know how to field check a 3-phase AC motor for proper operations.

3. Know grounds and shorts, and the proper way to test for them.

4. Be able to calculate current if given the number of volts and the amount of resistance in ohms.

5. Know about electrically operated control valves and how to troubleshoot if it will not actuate the valve.

6. Know the different units of measurements for electrical components.

7. Know what an Electrical Bus Bar is and why tightness is so important.

8. Know what a single-phase circuit is and how to fuse them.

9. Know how to measuring an unknown current, specifically with an ammeter.

10. Know what components require a parallel circuit for connection.

11. Knowledge of NESC Codes.

12. Be able to solve an equation based on Ohm’s Law.

13. Know where to find the specifications for wire conduit size.

14. Know when and why an Ammeter is placed in a circuit.

15. Know about solenoid devices and their uses.

16. What does an “infinite” reading in a solenoid coil show?

17. Understand Logic Gates.

Answer 1

1) Multimeter is electrical device used to measure voltage, resistance, check continuity of circuit. Value is measured using positive and negative probe.

2) Check motor megger and resistance value for its winding condition. Check for tightness of cable termination in terminal box and local control station both. Check alignment of start and stop button in LCS. Check proper lubrication of motor. When motor is running condition check for any abnormal noise if there.

3) Ground is always at zero potential whereas short is at potential with which circuit it is shorted. Check voltage between ground and earth it will be 0V and voltage between short and earth will be V volt.

4) Using Ohm's law, I=V/R

5) Motor operated valve is used to operate the valve using motor. If it is not operating check for healthiness of motor from both switchgear and field side. Check for motor megger, resistance value. Check alignment of start and stop button in LCS. Check contactor operation from switchgear side. If motor is found ok then check if the valve is stuck. If it is stuck then motor will take high current and will trip due to overcurrent.

6) Different units of measurements for electrical components are Voltage,current,resistance,power,power factor.

7) Busbar is a metallic strip or bus mounted inside switchgear panel which have constant voltage and constant frequency. Tightness is important because if it will be in loose condition then hot spot will develop and there is a chance of melting of bar and it may led to short circuit.Tightness also ensure proper alignment with other equipment.

8) Single phase circuit have a 3 wire in it. One is phase, second is neutral and third is earth. Protection can be provided by fuse by using in series with for short circuit protection.

9) Ammeter is installed in series with circuit across where current is to be measured.

10) Voltmeter require parallel circuit for connection.

11) The National Electrical Safety codes (NESC) is a US standard of the safe installation, operation, and maintenance of electric power.

12) V=IR

13) Conduit size is specified according to National Electrical codes.

14) Ammeter is used in series with circuit to measure the current.

15) A solenoid includes a coil of wire that is covered around a core made out of a metal. When a current is applied to the solenoid magnetic field develops. Electricity changes to magnetism then it changes to electricity and, therefore, these two forces are united into one.

It is used in locking system, solenoidal valve operation.It is used in computer printers, fuel injection gear used on cars.

16) Infinite reading shows that coil is opened and so it cannot be operated.

17) Logic gates are basic building block of digital system. The basic logic gates are OR,AND,NOT,XOR,XNOR,NAND,NOR. Here two inputs is used and it give one output corresponding to gates.