Battery Capacity for aTtraction Motor

Er, what's 160A multiplied by 12h multiplied by, oh, say 115%?

The usually don't calculate for 12 hours. 8 hours one shift. Then swap out batteries. The weight gain for the extra 4 hrs can be substantial depending on voltage an AH draw. This weight gain plus what is need for the supporting structure for the battery is wasted power.

It's also worth bearing in mind the motor is highly unlikely to be running at100% output for 100% of the time.

Here the traction motor is a short time ( s2- 60 min ) motor, what may be the effect and how can i find the battery capacity for it?

Does S2 represents drawing a constant load or FLA only for 60 min ?

I have searched about duty cycles of induction motor, but in everything they have mentioned only about , what they are.

Well i want to know about the starting current that S2 motors can have.

1) Well if i m using a S2 motor does starting current exist ? If it does, how much compared to other motors?

2) And if i use a drive does it automatically reduce the starting current on implementation?

" I know i m a little away from battery part but i need to know this."

You did not mention "induction motor"!

The data I gave in my last post [ #4 ] was thinking of a Direct Current motor. A current of 160 amp and 6 kW rating (shaft power) suggests about 40 volt supply rating. Electronic controllers are used with battery and Series wound DC motors.

But everything I wrote is equally true for an induction motor.

However, while for a DC series motor, rated torque, speed zero [starting], needs rated current - for an induction motor it takes about 6 times rated current. A drive cannot deliver zero frequency. An induction motor and its drive is high loss and heating until the "slip" [s] between rotation speed and synchronous speed is about 0.03.

If you want to know exactly what "S2" means, you must look at the standard to which the motor complies. The standard should be on the motor rating plate. College and big public libraries should have copies of standards or web access to them. Searching for the standard and S2 on the web will probably find the essential basics. But buying standards is very expensive for individuals.

There are simple formulae for induction motor torque and current in terms of slip and voltage. They are not much use unless you actually have some motor data and they only apply to rotors with simple slots and bars. But they are a useful tool.

Try searching for "induction motor" and "traction motor" in Wikipedia, the free encyclopedia

Actually i know what a S2 induction motor means , it is a motor which can carry a constant load within a given time say 60 min before reaching thermal equilibrium.

*I want to whether there is any difference in the starting current taken by the S2 induction motor or not, compared to other duty cycled induction motors ?

*And if there is , installation of a Drive without setting, does reduce the starting under testing ? I mean does it automatically reduce the starting current ?

Wrong - an S2 motor reaches its maximum temperature, for its insulation, after its rated time at its rated power from cold.

It is NOT in equilibrium at rated time, the temperature is still rising and would reach damaging levels if the loading continued the same beyond the rated time.

That is why it is a short time rating.

I believe "S2" indicates just the time rating at a constant load from cold. If you are talking a duty cycle of varying loads repeated continuously, I believe that would be "S3". As I wrote, you need to look at the standard the motor is made to meet [You did not get "S2" out of the air, did you?].

Starting current is another factor. Which you can best get by asking the motor maker. But I believe any good motor can withstand "locked rotor" current for about 30 seconds - so why worry?

Whether an electronic drive automatically "learns" the motor parameters depends entirely on what a particular maker designed it to do - read the drive specification.

I suggest you stop guessing, or hoping the drive electronics will do the job for you...

1. Get a 230/110 V 50/60 single phase tool safety transformer. 1 kVA rating (10 amp secondary).
2. Get a 230V 1 kW "firebar" resistance space heater.
3. Put the firebar in series with the 230V supply to the transformer as a current limit ballast. If you could get a 3 kW firebar and 3 kVA transfo with a lower secondary voltage you could do a test at closer to rated motor current. Hint, any good transfo can withstand short circuit for a second or so.
4. Lock the motor rotor so it cannot turn.
   
5. Connect transfo secondary winding to motor windings, via ammeter.
6. Measure winding voltage and current.
7. Voltage divided by current = winding impedance W ohms.
8. Rated motor voltage for winding tested divided by W = approximate maximum starting current.

You may find the following internet address helpful, since the document describes the induction motor equivalent circuit.....

http://www.ece.msstate.edu/~donohoe/ece3183asynchronous_synchronous_machines.pdf