output from transformer is coming not as expected

[Brumby]

Had a closer look at your photo - and, yes, transformer 4 only has two wires on the secondary.

Just to be clear ... the description 12-0-12 can be written as 0-12-24 or 24-12-0.  They all are just as correct.  Transformers 1, 2 and 3 can be described as having 0-12-24V secondaries, with only the 0V and 24V connections used.

This is not compatible with the 0-12V secondary of transformer 4, for the symmetrical design you created.

[VickySalunkhe]

So sir do you mean
Because of transformer 4 or the connection (2)
The full supply is not given to the load .and it will power the supply only after the voltage readings goes down to 36V?

[Brumby]

(1) can only ever provide a maximum of 36V DC.

That means that (1) cannot contribute any power until the voltage of (2) has dropped to below this value.


For your circuit to work as expected, transformer 4 must have the same 24V output as the other three.

[Raj]

Add 2 separate current limiter and diodes to the mix assuming you want dc volts

it'll also make it start softly

[adras]

Let's try the diagnostic somewhere else, BenKenobi already mentioned it but it seems like everyone missed it.

Is your motor running at full speed when it draws just 1.5Amps? If this is the case the motor doesn't need more current. Try to slow it down while it is running, give it something to work, put a load on it, try to slow it own with your fingers, then the current will increase. And everything is working as it should.

[Brumby]

Before we try and get the OP to do anything else - how about we focus on getting them to sort out transformer 4?

[VickySalunkhe]

The motor is running on the full speed

I have tried stopping it but the voltage levels go down to 37v and push occurs from the motor and thr voltagr level starts again from  52v snd speed starts from 0 again

[adras]

That sounds good, how about the current draw? Does it still use only 1.5Amps when you try to stop it or does the current increase?

[VickySalunkhe]

Sir i have done the testing of my transformer individually
With a load of graphite present in a pencil it did get burst out in few seconds but i got the readings
Resistance on which i tested the transformer was around 7ohm

Readings for transformer 1,2,3 is almost same
Transformer 1,2,3 (12-0-12v 5A)
254V AC IN
29.8V AC OUT
26.3V DC OUT (AFTER RECTIFIER)
39.9V DC OUT (AFTER 6.6mF capacitor)
MAX CURRENT USING LOAD   5.9A

Transformer 4 (0-12v 5A)
254V AC IN
14.3V AC OUT
12.9V DC OUT (AFTER RECTIFIER)
19.14V DC OUT (AFTER 6.6mF capacitor)
MAX CURRENT USING LOAD   5.2A

Through all this reading i think the transformer is working fine
But I don't understand why the controller/motor is not able to fetch the current more than 1.5amp
Do tell me which other test reading should i provide
So you all can help me resolve my issue properly

Thanks

[Brumby]

Thank you for those readings.  They indicate the four sections of the power supply are basically functioning properly.

While there is still an issue with transformer 4 not being the same as the other 3, if the maximum current draw is less than 5A, it doesn't really matter.

The next question is: How thick and how long are the wires which carry the heavy current?  All wires have some resistance.  The thinner they are and the longer they are means higher resistance - and that will limit the current that can pass for any given voltage.

Some measurements can be helpful here.

The simplest is to select a reference point and connect one lead from your multimeter and leave it there for the rest of these measurements.  Connect the controller and motor so they are drawing the 1.5A current. Then measure the voltage at each end of each current carrying wire.  It would be good to draw a schematic and write those values at the appropriate places.



When you do want to draw more than 5A though, you must either replace transformer 4 with one the same as the other 3 or get another one the same as transformer 4 and connect it in series to give the necessary 24V AC (nominal).  (If you do the latter, this is where phasing is important: connecting the two secondaries in series will provide an AC voltage of either 0V or 24V, depending on whether you connect them in phase or out of phase.  You only need to get 24V output to know you've got it right - and this is fed into the diode bridge.)

[Brumby]

I understand we have a language barrier - and I have been trying to understand, but I am a bit lost here.  Can anyone else shed some light?

[adras]

Readings for transformer 1,2,3 is almost same
Transformer 1,2,3 (12-0-12v 5A)
254V AC IN
29.8V AC OUT
26.3V DC OUT (AFTER RECTIFIER)
39.9V DC OUT (AFTER 6.6mF capacitor)
MAX CURRENT USING LOAD   5.9A

Transformer 4 (0-12v 5A)
254V AC IN
14.3V AC OUT
12.9V DC OUT (AFTER RECTIFIER)
19.14V DC OUT (AFTER 6.6mF capacitor)
MAX CURRENT USING LOAD   5.2A

Those two values should be the same I guess. So transformer 4 seems to "broken". So let's get rid of that transformer. Only use transformer 1 and 2 which are identical. Both together provide at least 5Amp. Use only these two transformers, and check if the motor is using more current, something like 5Amp. If that works, it shows that transformer 4 is the problem. If it still not works, the motor is running idle and doesn't need more current and you need to give it some load like a propeller.

[VickySalunkhe]

The next question is: How thick and how long are the wires which carry the heavy current?  All wires have some resistance.  The thinner they are and the longer they are means higher resistance - and that will limit the current that can pass for any given voltage.

I will try to change something in new response
I too felt the old response a little confusing

Sir i have tried two combinations of connection  (main supply, psu, motor and controller)
as far as the length of wire is concerned
I have not measured the thickness but i have measured the resistance of wire
The wire is about 70meter long having a resistance of 3ohm which is used

1st connection
The long wire is connected before the psu (between main supply and psu) and then after the psu controller and motor is connected with a wire in between having a length of less than a 30cm
   
2nd connection
This is just opposite of above
Long wire is connected after the psu (between psu and controller).
  In this type i felt less torque compared to (1st connection)

Is this the answer you asked for ?
If not plz do tell me what readings you wanted to give you.

Thanks

[jm_araujo]

This topic is very confusing, and it seem it's approached the problem in the wrong angle.

I couldn't find any reference from the OP that the motor is loaded. The current on the motor will only increase if it has a load. If if running without a load it's expected that the current is low.

Also it's not very good idea to parallel 2 different power supplies, but in your case as they're not regulated the diode bridges will avoid any current flowing between them. The lower voltage one will only contribute when the parallel output voltage is lower than the voltage without load.

[VickySalunkhe]

Sir i have connected the controller and then the controller with motor only

Do you mean i need to connect any other load to the psu with the controller+motor to draw more current?

[jm_araujo]

A load to the motor is something mechanical connected to it. A propeller, a water pump, a bicycle wheel. It depends on the application.

A motor converts electrical power to mechanical. If it has no mechanical load, all the electricity that's consumed is for the inefficiencies (drag, winding resistance, etc).

[IanB]

as far as the length of wire is concerned
I have not measured the thickness but i have measured the resistance of wire
The wire is about 70meter long having a resistance of 3ohm which is used

This is very wrong. Why is the wire so long? A wire conducting power should be as short as possible and should have a resistance of a fraction of an ohm.

[VickySalunkhe]

Sir my ultimate aim was to build a psu to run the motor
JUST FOR TESTING PURPOSE


in later stage I'll be purchasing li-ion cell pack of 13s4p
But that is costing me too much at the stage i am present so I thought to think for that in a later stage

So i thought to build a psu to give the power to motor for testing purposes
I am building an E-Bike as a college project

So the motor here is (Hub motor with wheel)

Thats why i have used 70Meter of wire to test the body of bike and other stuffs

[VickySalunkhe]

Motor used here is a hub motor
Used in a vehicle so ultimately i am giving a mechanical load on it...

[adras]

Can you run a test with a wire length of 30cm? I mean the wires between motor and transformer

[Ian.M]

Due to the voltage drop from a long cable  or a poorly smoothed or regulated supply the operating conditions wont be at all similar to operating your motor controller from batteries, as intended in the final application.

You'd probably do better to source four used 12V Lead Acid car batteries of similar capacity, which could be in relatively poor condition as long as they can still hold a charge and don't have any dead cells so hopefully would be fairly cheap.   Batteries with removable caps so you can check the acid level and top up with distilled water are preferable but they are fairly rare nowadays.


Connect them in series to get a ripple free nominal 48V, that closely resembles the output of your proposed LiPO pack.  The load circuit should either be fused or have an appropriately DC rated circuit breaker, with the fuse or breaker rated to interrupt a minimum of 60V DC, as such a set of batteries even in poor condition could put a very large current through a short, and there is a risk of explosion if you short a recently charged Lead Acid battery and there is a cracked internal connection that cant carry the full short circuit current, or if the electrolyte boils due to Joule heating. 

Then you need to charge them - you could do so one at a time from a CC/CV bench supply with a series Schottky diode to prevent reverse current if input power is lost, or you could build a charger for them - probably the easiest would be 48V RMS from your transformers, a bridge rectifier and a series ballast resistor to limit the maximum charging current + a relay to disconnect its input power when fully charged.   Due to the unknown history of the batteries they are likely to have dissimilar actual capacities so will require balancing - for that you can simply add a shunt regulator across each one set to about 14V, that can pass the full charger output current.  Detect when all four shunt regulators are passing significant current, and start a timer to terminate the charge using the relay and disconnect the shunt regulators.  Charging should ONLY be performed with adequate ventilation.  Alternatively if you can obtain four small smart float chargers for Lead Acid batteries, with two wire mains leads (no ground), simply connect one across each 12V battery. 

[VickySalunkhe]

Sorry but the readings which i posted last time out of that
One of the transformer reading was wrong

New and correct readings are as such

259V AC IN

Transformer 1 (12-0-12v 5A)
29.8V AC OUT
26.3V DC OUT (AFTER RECTIFIER)
39.9V DC OUT (AFTER 6.6mF capacitor)
MAX CURRENT USING LOAD   5.2A

Transformer 2 (12-0-12v 5A)
14.8V AC OUT
13.01V DC OUT (AFTER RECTIFIER)
20V DC OUT (AFTER 6.6mF capacitor)
MAX CURRENT USING LOAD   4.3A

Transformer 3 (12-0-12v 5A)
29.9V AC OUT
26.6V DC OUT (AFTER RECTIFIER)
40.8V DC OUT (AFTER 6.6mF capacitor)
MAX CURRENT USING LOAD   5.2A

Transformer 4 (0-12v 5A)
14.3V AC OUT
12.7V DC OUT (AFTER RECTIFIER)
19.8V DC OUT (AFTER 6.6mF capacitor)
MAX CURRENT USING LOAD   4.3A

For a complete psu giving out 59V DC (without load)
(1)Transformer 1&2 are in series
(2)Transformer 3&4 are in series
(1) & (2) are in parallel

[adras]

Ok, to simplify things, please run the following test.

Use Transformer 1 and 3 only to power the motor. Use 30cm/11" cables between transformer and motor.

@All, if the wires have a too small diameter they should get hot/burn through, right? I doubt that too slim wires would just reduce the current flow in this "high" current scenario. 

[Brumby]

@All, if the wires have a too small diameter they should get hot/burn through, right? I doubt that too slim wires would just reduce the current flow in this "high" current scenario.

It depends ... but significant voltage drop over short lengths would be expected to heat things up noticeably.

Sorry but the readings which i posted last time out of that
One of the transformer reading was wrong

Transformer 2 (12-0-12v 5A)
14.8V AC OUT
13.01V DC OUT (AFTER RECTIFIER)
20V DC OUT (AFTER 6.6mF capacitor)
MAX CURRENT USING LOAD   4.3A

From this it seems you have only wired half of the secondary (the photo seems to support that).  In this case, the total voltage of (1) and (2) are close, so all 4 transformers of the supply can be used as you originally intended. 

From the current tests, you say "MAX CURRENT USING LOAD".  But what is the load?  This is very important for the readings to be meaningful.

Aside from the precise current capability, I am feeling less concerned about the supply at this point - but, as has been mentioned earlier, there are some questions surrounding the operation of the controller and the specific loading of the motor...

[VickySalunkhe]

A load of graphite present in a pencil is used as a load, it did get burst out in few seconds but i got the readings
Resistance on which i tested the transformer was around 7ohm