Hey everyone any help on these questions will be great, I have the exam Thur 2pm, will be spending next 2 nights after work trying to understand but me and motors seem to struggle more then often, can anyone recoomend a decent motor book to study from?

1. Speed control of a 3 phase induction motor is achieved by varying the
A Resistance in rotor winding
B Voltage applied to the stator
C Rotor winding inductance
D The number of stator windings

2. The purpose of capacitor in a capacitor start motor
A Provide power factor correction
B Limit the starting current
C Provide an increased phase displacement
D Smooth the a.c. supply

3. When starting a 400v 3 phase cage rotor motor using star delta starter, the voltage across each stator phase is
A 400v start 230v run
B 133v start 230v run
C 133v start 400v run
D 230v start 400v run

4. cage rotor motors are considered to be best running at
A Variable speed
B Constant speed
C High speed
D Low speed

5. A rotating field is produced in a 3 phase cage rotor motor when connected to
A Rotor
B Stator
C Commutator
D Slip Rings

6. The thermal trip on a direct on line starter is to
A Provide magnetic overload protection
B Provide thermal overload protection
C Provide remote starting
D Prevent motor over speed

7. A motor with a wound rotor has windings on
A Rotor only
B Stator only
C Stator and rotor
D Commutator & field

8. Connections made to rotor windings on a 3 phase induction motor use
A Mutual inductance effect rotor and stator
B Commutator and brushes
C Capacitor link to rotor windings
D Slip ring and brushes

9. A single loop of wire connected to slip rings rotated in a magnetic field. Voltage measured at slip rings will be
A D.C.
B Unidirectional
C Intermittent
D A.C.

10. A capacitor start and run single phase induction motor runs as
A Quad phase motor
B Single phase motor
C Two phase motor
D Three phase motor

11. A 400v 50Hz has a line current of 50A and 0.8 lagging, The power dissipated will be
A 20KW
B 9.2KW
C 27.712KW
D 16KW

12. The reactance of a 1uf capacitor connected across a 50Hz supply is
A 3.18 ?
B 31.8 ?
C 318 ?
D 3.18 ?
13. Cage rotor induction motor are considered to be
A Variable speed machines
B Low speed
C high Speed
D Constant speed

14. Which of the following is suitable for starting a 3 phase rotor cage induction motor
A Auto transformer and rotor resistance
B Rotor resistance and capacitor start
C Auto transformer and star delta
D Capacitor start and star delta

15. In a 2 pole generator the brushes on the commutator pick up the voltage generated which is
A A.C.
B Unidirectional
C Intermittent A.C.
D Steady D.C.

16. A 3 phase 4 pole motor 50Hz induction motor has a slip of 4% the actual speed of the motor is
A 1500prm
B 1440rpm
C 1400rpm
D 1359rpm

17. When a capacitor start capacitor run single phase induction motor reaches speed, a centrifugal switch
A Removes all the capacitance connected to the field windings
B Reduces the number of field windings
C Leaves on the run windings connected
D Reduces the capacitance connected to the start winding

18. The rotor conductors of a 3 phase cage rotor inductance motor are constructed of a solid conductors
A Shorted at each end of rings
B Connected to the supply by slip rings
C Connected to the supply by commutator
D Forming a star connection

19. The number of pair windings in a single phase capacitor start induction motor is
A One
B Two
C Three
D Four

Edited: 04 September 2007 at 08:18 AM by dean_sussex

passed!! Thank god for that, dismall statistics but a pass is a pass, 75% part 1 and 50% part 2, Feel could have got higher mark but as I didn't have my calculator with me, thought it was in my folder but must have fell out somewhere along the line still managed to pull through.

2330 Level 2 and 3 done for me now, next step 2381 + 2391 as well as NVQ 3 on top of HSL exam for JIB card, oh the joys of it all.

Well done, don't feel too down about the pass, the Level 3 exam despite what may be said on these forums from time to time, is a very difficult exam indeed and there have been a huge amount of failures this year.

You will have no difficulties with the 2381 at all or the ECS test and the NVQ 3 is (usually for adults) quite an easy process. The 2391 requires some study but I recommend getting a bit of experience first anyway.

Onwards and upwards!

-------------------------
http://www.electricalqualifications.co.uk
http://www.electricalexams.co.uk
http://www.electricalrevision.co.uk

hi there any chance of the answers for the above questions as i have now failed twice and am losing the will to live cheers clive ?

I am curious as to where these questions came from. Some are incomplete, some are ambiguous and some are pretty irrelevant.

For instance, (1) speed control of a 3 phase induction motor is achieved by varying the frequency an inverter. Any other method is 500 years old.

(2) A capacitor is there to provide phase displacement, not "increased" phase displacement. "increased" suggests that it is already displaced to some extent which, it is not.

(3) D

(4) Constant speed

(5)Badly worded but I think it's alluding to the stator

(6)Again, not worded very clearly. Whats a "thermal trip"? the overload? I suspect so ergo it's thermal protection.

I'll go and have my tea now, maybe you should be sourcing some better questions for the exam, all the books on my website have better quality and more relevant questions on them.

Best of luck with the resit.

-------------------------
http://www.electricalqualifications.co.uk
http://www.electricalexams.co.uk
http://www.electricalrevision.co.uk

I have to say nsambrook alot of these question are very much badly worded, however that was exactly how they were on the exam, many of those questions were from many students that had failed many times but still could not find the answers as the question just wasn't clear enough.

I had a pack given to me by my tutor with all the questions people had through 2330 301 exam which did help me with what to expect but didn't help as wasn't clear and Trevor Linsley advanced gave me great help but yet wasn't 100% clear with motors, well for my brain and those questions, but hey ho have passed and thats all that counts, NVQ 3 portfolio working on now and then 2381 but wondering if I should wait for 17th? or sit the 16th exam still thinking about that one.

Edited: 22 September 2007 at 09:30 PM by dean_sussex

You are probably right. The City and Guilds have reviewed all those who haven't passed over the last 12 months and have changed some grades.

They also have mentioned that they will be changing some of the more badly worded questions so it looks like you will have been part of the guinea pig program for the Guilds. They are also allegedly going to change the scheme of work so that those of us who have to deliver it have some idea as to what we should be teaching.

-------------------------
http://www.electricalqualifications.co.uk
http://www.electricalexams.co.uk
http://www.electricalrevision.co.uk

Blimey there is hope for us yet, did feel abit of a guinea pig through out the course also felt sorry for tytors having lack of direction from city and guilds, I'm happy I've done my first part and waiting for 17th edition to print, also have been thinking about PAT testing if would be worth my time?

Lots of directions to head into, main thing is finding the work as long as that keeps coming my way I'm happy

Personally I haven't done the PAT course, I think it is aimed at people who do it regularly and although money can be made, I always hated doing it. There is very little call for it at our place and it hasn't run for some years.

I'd probably hold now for the 17th, you've done the hard work and right route in my opinion now get on and earn some cash

-------------------------
http://www.electricalqualifications.co.uk
http://www.electricalexams.co.uk
http://www.electricalrevision.co.uk

well done dean,
ECS health and safety questions download here>>

http://www.jib.org.uk/ecs031.htm

hope this helps :-)

-------------------------

"knowledge is power"-"wisdom the 3 pin plug for it"

ROB

Thanks Rob I've printed it all off and will have a heavy read, appreciated

your welcome ;-)

-------------------------

"knowledge is power"-"wisdom the 3 pin plug for it"

ROB

answers: 1-A for SRIM and B for SCIM
2-C
3-D
4-B
5-B
6-B
7-C
8-D
9-D
10-C
11-D
12-D BUT IN KILO OHMS
13-D
14-C
15-A
16-B
17-D
18-A
19-B

Bit confused on somethign with this one:



PF=0.8
IL=50A
VL=400V

P=/3 VL X IL X PF
Is that the right formula?
I've calculated in to different ways, first way:

P=/3 400v X 50a X 0.8= this seemed to give a syntax error on my calculator?

When i did it a 2nd way:
400v x 50a x 0.8=16000

Is this the right way? and does 50hz come into this at all?

No hertz doesn't come into it and you are doing it properly, at least in so much as you have the right formula anyway.

Instead of doing the square root of 3, use 1.732 instead or put the square root of 3 into brackets first.

-------------------------
http://www.electricalqualifications.co.uk
http://www.electricalexams.co.uk
http://www.electricalrevision.co.uk

Hi all new to site ?
To question 12 I come up with 314.1 ohms where am I going wrong help please

Also need a formula please ? A current in a coil changes from 5 amps to 2 amps in 0.05 seconds and induces a voltage of 30 v in the coil . The inductance of the coil is?