Progress and not getting wet

[Heinz]

"9.9A 745W and with the water on it's 10.8A 550W"

9.9amps 745watts = 75volts ?

10.8amps 550watts = 51volts ?


I think your readings must be off somewhere ?  what does the plate on the motor say ?

how long is the cable to the motor, and is your plug in power meter at the motor end or the other end of the cable ?

if there's a long cable, there will be a volt drop between one end and the other (mains > motor)... when you start to generate it will change around so the high volt end is at the motor.... I wonder if this could explain some of the problems with the meter readings ?

can you turn the water on slowly at watch the meter at the same time, so you can watch for the meter reading dropping and then rising again ?
(as it needs less power to spin, and then starts to generate power)

2.2KW 240v 14.4A 1phase, but it's now abandoned in favour of a three phase motor.
Plug in power meter is at the workshop end of 200m of cable. I did check the cable loss with an on line calc. before buying the cable and although I can't recall the loss right now, it did seem acceptable @ 10amps.
I can't see the plug in power meter and turn on the water at the same time (yet) but I did incorporate a loop on the live cable at the turbine end for a clamp meter, thought it would be useful to be able to watch the amps and adjust jet angles for max. Completely forgot about this loop until now..... Never mind, I'll not forget when setting up the 3ph motor.

H

[Heinz]

If you connect your IMAG to the turbine with a freewheeling clutch eg Sprag clutch

you can then start it as a motor and then gradually increase the supply of water to the turbine until it goes into generator mode. You are then in sync with mains all the time.

This seems a little over complex for a turbine, perhaps different for a water wheel.
If I was starting the motor from rest, no current is flowing, turn on the power, current flows, motor accelerates to sync-slip speed. If the turbine is spinning, no current is flowing, turn on the power, current flows, motor/gen slows to sync+slip speed. It's the same thing, except the start current will probably be less for the turbine as the motor is already close to it's sync speed?

H

[knighty]

edit:

did you mean 10volts drop across the cable ?
(that would make more seance)

10amps loss would be a lot


i think you really need to measure the power at the motor end to see what's going on... volts and amps...
(with the motor spinning, water on and water off)

[Heinz]

edit:

did you mean 10volts drop across the cable ?
(that would make more seance)

10amps loss would be a lot


i think you really need to measure the power at the motor end to see what's going on... volts and amps...
(with the motor spinning, water on and water off)

No, confusion, I meant the cable losses at 240v and 10amps were low. 10 amps is the max I expected the cable to carry, not the loss.

H

[noah]

This seems a little over complex for a turbine, perhaps different for a water wheel.

With the size of IMAG you are talking about the jolt that the IMAG gets when connecting to mains at over sync speed is not going to matter very much to the grid or to your IMAG (as long as it is not vastly overspeed). However to give even the tiniest of nods towards legality you need to at least attempt some sort of synchronisation.
I`m surprised that there are not 40 replies telling you to cease and desist your tinkerings as they are illegal and dangerous. They could be right- so be careful and check out some older posts on IMAGs, G83.

[guydewdney]

as said above - well, implied, - connecting a 'poxy' few kw induction motor to the grid isnt going to affect anything - machine shops do this all the time with lathes etc etc with no ill effects at all.

[Heinz]

This seems a little over complex for a turbine, perhaps different for a water wheel.

With the size of IMAG you are talking about the jolt that the IMAG gets when connecting to mains at over sync speed is not going to matter very much to the grid or to your IMAG (as long as it is not vastly overspeed). However to give even the tiniest of nods towards legality you need to at least attempt some sort of synchronisation.
I`m surprised that there are not 40 replies telling you to cease and desist your tinkerings as they are illegal and dangerous. They could be right- so be careful and check out some older posts on IMAGs, G83.

I was kind of wondering when the 'stop what you're doing' replies would take over ruin the thread....

H

[knighty]

synchronisation is easy.... turn the power on before you turn the water on

as a side note... I turn 40kw+ motors off and then back on again while they're still spinning at work all the time and it doesn't do any harm... has never even dimmed the lights... which turning the motor on the first time (from stop) does !

[regen]

I was kind of wondering when the 'stop what you're doing' replies would take over ruin the thread....

H

Dont stop H!  This is one of the most interesting threads on this site.  Just sorry I dont have enough knowledge to participate - but I am learning.

The problem with getting the wire through the pipe may well save me a lot of time and effort in the future!

Regen

[Heinz]

Spent most of the day messing around with motors and capacitors instead of doing real work  
Screwed a single phase motor to a bench and used it to belt drive my hopeful turbine single phase motor. Nothing I did today would persuade it to generate anything much. Spun at over it's speed, then switched on, it just dragged down the donkey motor to it's normal running speed. Tried adding more capacitors to the RUN capacitor. This made little or no difference.
Tried the three phase motor belt driven in the same way and it's quite happy to be driven slightly over normal speed and generates if it has capacitors in the C-2C layout, no capacitors = no generating. No surprise there.... The best cap. sizes seems to be C =30uF  2C =60uF which make it generate 5.8A which sounds good to me, but there is a problem. If the 3ph motor has the C-2C caps. it (not surprisingly) self sustains. Unplug it from the mains but leave the donkey motor running and it puts out around 360volts which kind of scuppers the whole 'keep it simple, cheap and safe' idea.
Time for cup of tea and a rethink. Suggestions welcome.....

Heinz

[Heinz]

Did some nettle tea drinking, slept for a while, did some thinking. If a 3ph motor without capacitors will run on single phase, which it will although it needs a spin to start it, then it must work backwards and generate. Tried this again this morning while avoiding doing paid work again. Spun it at 1600rpm, plugged it in to the plug in power meter and it does appear to chuck out 2.8 amps with the rpm just above 1500 on my ancient mechanical tach meter. The bare 3ph motor runs at just below 1500rpm, so if it's being driven above sync speed and there 2.8A flowing, it must be generating. May have to acquire an old spinning disc elec. meter to clarify which way the amps are flowing....

Off to stand in front of a milling machine in a dark workshop while the sun blazes down outside, or on the other hand I might not 

H

[knighty]

can you connect an amp meter inline with it ?

you'll see +amps for power in and -amps for power out ?

they're pretty cheap and you'll probably want one anyway for when it's up and running so you can keep an eye on it ?

[Heinz]

can you connect an amp meter inline with it ?

you'll see +amps for power in and -amps for power out ?

they're pretty cheap and you'll probably want one anyway for when it's up and running so you can keep an eye on it ?

I can't see that working on AC ?? or am I just being thick again?

H

[knighty]

I can't see that working on AC ?? or am I just being thick again?
H

I don't know... I think most digital meters will do it ?
(pretty sure mine does... but I think I've only used it like that once before....)

[Heinz]

Update.
Spent Saturday turning up inserts to sleeve the runner hubs to fit the 3ph motor and modifying the turbine base to fit the motor. Sunday was cancelled due to children and feeling like sh*te with the cold. Today I should have been stripping a customers gearbox, but it wasn't raining, so decided to fit the modified turbine and see what happened  
Quad bike and trailered it back down the field, what did we do before quad bikes? Dragged it the last wee bit down the bank with a rope and connected it up. Back up to the workshop and temporarily connected my latest Ebay purchase, a used spinning disc type meter to make it obvious which way the power is going. Pity Fedex played football with it and shattered the bakelite   never mind, a replacement is on it's way and I've bodged it back together enough to work. Hooked it all up, plugged the turbine cable into the plug in power meter and turned on the power with the contactor. Back down the field. Turned on the water and roughly adjusted the jet aim for the least noise, but highest RPM. Switched on the motor/generator. Back up to the workshop on Rhonda the Honda    It's making 190w at the moment   There's going to be more power there, just haven't had the time or daylight yet to tweak it. Jet angle and size need adjusting, loads of excess water at the header tank which could be going down the penstock and the other runner to try....  

H