T2 Mock questions

m.j.w

Just going over a mock paper here and unsure of a few answers. Can someone tell us what they are and does anyone have any other mock papers. The questions are:

1 - All cable connections should be accessible for inspection exept cables

a- swimming pools
b- overhead lines
c- enclosed in non flammable material
d- sheathed in asbestos

2 - In a star connected motor the supply voltage is connected

a- to all 6 connections
b- across 2 windings in series
c- across 2 winding in paralell
d- across 3 windings in series

3 - In a delta connected motor

a- the supply is connected across each winding
b- the supply is connected to one end of each winding
c- the neutral point of the windings is at zero voltage
d- the neutral point of the windings are connected to the neutral of the supply

4 - Which of the following statments is correct

a- When a motor is single phasing the current and torque is low
b- In a star connected motor 1 winding will burn out if the motor is left single phasing
c- In a delta connected motor on winding will burn out and the other 2 windings over heat if the motor is left single phasing
d- Once a motor attains its rated speed single phasing will not cause any damage to the motor windings

5 - When a motor is operated through a star/delta starter

a- The starting current and torque is reduced
b- The starting torque and current is increased
c- The starting current is reduced and the tourque is incresed
d- The starting current is doubled and the starting torque is halved

6 - A single phase motor hums but the shaft does not rotate. This could be due to

a- One of the windings open circuit
b- The switched siezed in the on position
c- Both of the windings open circuit
d- No load being present on the motor

7 - When a motor is connected in delta and the resistance of each winding is 6R what reading will you get if you measure accross U1 and W1

a- 6R
b- 12R
c- 4R
d- 3R

Thats the lot, i would go for these but im not to sure
1- d
2- b
3- b
4- c
5- c
6- b
7- b

M cebee

1-c
2-b
3-a
4-b
5-a
6-capacitor?
7-c

m.j.w

cheers for the answers, could you explain how the resistance across the two winding is 4 ohms. are they not all connected since they are in delta so how does it work out at 4

M cebee

6 ohm in parallel with 12ohm(6+6)


they're not defintive answers:D

2011

6 is a

A single phase motor does not have a "naturally occuring" rotating magnetic field. Agree with M Cebee on the others.