I would really appreciate help in answering any of these questions. I am new to learning about generators, however, I must be able to answer these questions. Please help if in any way possible. Thanks!



1) What type of insulation material is used for generator stator windings?

2) What is the stator and rotor core construction?

3) What is an el CID tests?

4) Where are RTDs usually located inside generators?

5) What type of systems are used to regulate generator gas temperatures?

6) What is the generator capability curve and how does it work?

7) How does the DC power from the exciter get to the rotor windings?

8) What are retaining rings used for and what are they usually made of?

9) How do we calculate the amperage in that a generator produces knowing the design voltage and design KVA of the generator?

10) What is MLE and OXL?

11) How is lagging and leading vars regulated on generators?

12) How long can generators motor? What can occur if they motor too long? Should there be trips associated with motoring?

13) Why is hydrogen used to cool the generator?

14) Why is it necessary to purge the system from air to CO2 to hydrogen?

15) What system is used to measure hydrogen purity?

16) What is the core monitoring system?

17) What prevents a generator from exceeding its rated voltage?

Wow thats ALOT of questions. Your questions are fairly basic and can be understood by reading power gen basics books or IEEE generators. I will do my best to help answer your questions. I hope im not doing YOUR homework for you! j/k


1) What type of insulation material is used for generator stator windings?
epoxy resin and newer non metallic materials. (MIcapal or GEGARD)
old generators used asphalt

2) What is the stator and rotor core construction?
this is a book in itself!

3) What is an el CID tests?
The electromagnetic core lamination fault detection technique is known as EL CID
EL-CID uses a low core excitation level (about 4% rated flux) to establish a magnetic
field within the core. A highly sensitive, miniaturized sensing coil, or chattock, is used
along the core surface to detect fault currents which will result from core insulation damage.
A signal processor located in the control system computer is used to measure, record and report
these faults. EL-CID has been proven to be especially valuable on machines where core loosening has been more prevalent.
4) Where are RTDs usually located inside generators?
in the stator area and imbedded in windings
5) What type of systems are used to regulate generator gas temperatures?
heat exchangers...water, air cooled, etc.
6) What is the generator capability curve and how does it work?
sets the limits of the generators capability... graphed on MVAR vs. MWATT
7) How does the DC power from the exciter get to the rotor windings?
dc, to cables to the collector, brushes used to transer field current to rings which connect to the rotor windings.
8) What are retaining rings used for and what are they usually made of?
to retain the field bars
9) How do we calculate the amperage in that a generator produces knowing the design voltage and design KVA of the generator?
ohms law!!! dont forget about reactive power!
10) What is MLE and OXL?
min excitation limit and over excitation limit.
11) How is lagging and leading vars regulated on generators?
by raising and lowering excitation... via DCS or within the excitation system.
look up AVR control, PF and MVAR control functions

12) How long can generators motor? What can occur if they motor too long? Should there be trips associated with motoring?
not recommended to motor a generator unless you are performing a static start. you can heat up the stator core and cause severe damage.
yes there should be trips.. relay 50RE is the key

13) Why is hydrogen used to cool the generator?
great insulating medium

14) Why is it necessary to purge the system from air to CO2 to hydrogen?
what causes combustion? AIR, HEAT, FUEL, and BOOM!
need to remove the air before introducing hydrogen. Co2 helps that and pushes the air out of the generator.

15) What system is used to measure hydrogen purity?
I perfer eones DHCP

16) What is the core monitoring system?
To determine if you are overheating your generator. Chemically and thermally stable Tagging Compounds have been devised enabling the specific area of overheating to be identified. The compounds are incorporated in trace quantities in protective coatings applied to critical areas of the generator and can be detected by the core monitor

17) What prevents a generator from exceeding its rated voltage?
a SMART excitation system.
typically auto voltage regulator set for 1.10pu of rated terminal voltage on the stator
field is regualted to 102% of AFFL.

i hope i have answered some of your questions!
I LOVE this WEB SITE.. spread the word.

Maybe you could enlighten the rest of us with some deeper explanations?

Hmmmm?


#6. So what are all those other diagonals and semi-circles for?

#7. You sure about this one are you?

#9. I plug my numbers into Ohm's law formulas. Something seems to be missing. The numbers are not coming out right!

#12. "Relay 50"???

#13. "Insulating medium"???

#14. "Air, Heat, Fuel and BOOM!"? Maybe you could explain this one.