Help with Water Pump

[KeepItSimpleStupid]

@Joe
Are the coils open to the water or are they in epoxy?

 

[alec_t]

@()blivion
So, we'll assume the OEM FETs/BJTs have some inbuilt protection. But for designing our PDM we'll have extra.
@ronv

I am wondering if 6 amps for the current limit is to much

The OEM controller chip (LM2576) limits at ~6A, so should be ok if we switch off completely after, say, 0.3 sec at >3A, or 0.5 sec at >2A ?
@KISS

We really don't have to do ALL of the controller

Not if Joe can just salvage the critical parts. I was thinking perhaps most of the OEM controller pcb could be left as is, with just the odd track snip and a couple of wires brought out to our circuitry, if we knew the OEM layout.
Do the 68uH/1000uF correspond to the datasheet's 100uH/1000uF switcher filter?

That LC filter will do some current limiting too.

For a few mS, yes. Unfortunately rotor lock is likely to last much longer .

 

[KeepItSimpleStupid]

Not if Joe can just salvage the critical parts. I was thinking perhaps most of the OEM controller pcb could be left as is, with just the odd track snip and a couple of wires brought out to our circuitry, if we knew the OEM layout.
Do the 68uH/1000uF correspond to the datasheet's 100uH/1000uF switcher filter?

Then the critical area is those 6 parts; 2 transistors and 6 resistors are the most critical.

Shutdown pin access might require surgery.

On page 19, there is an optional output ripple filter of 20 uH and 100* uF labeled L2 and C1. The main supply on the datasheet is L1 (100 uH) and C1 (2000 uf).

The OEM controller uses 1000* uf @ 25 for C1 and as yet unmeasured inductor for L1. There is 1000 uf @50 ||1000 uf @ 50 for Cin

* These capacitors are probably not high ripple and 25 VDC is too close for comfort and need to be changed.
1. And it needs two diodes (one, the reverse biased output diode, can be added axially easily by drill/scratch/solder)

Reminder: The system is fed by a 8A 800 V bridge and 1000 uf || 1000 uf @ 50 V capacitors.

@Joe
Those 6 parts should be in the area of R1, R2 on page 19 of the datasheet. These resistors are 5 band and all end in brown, so the one by T2 is RED-RED-BLK-BRN-BRN. In circuit, I measured 2188 ohms. That value should be 2200 1%, (2188-2222 ohms) The last BRN is 1%; RED, RED, BLK are 3 significant figures and BRN is a multiplier of 1 zero. Not your typical resistor.

 

[salty joe]

@Joe
Are the coils open to the water or are they in epoxy?

Covered in epoxy.

@Joe
Those 6 parts should be in the area of R1, R2 on page 19 of the datasheet. These resistors are 5 band and all end in brown, so the one by T2 is RED-RED-BLK-BRN-BRN. In circuit, I measured 2188 ohms. That value should be 2200 1%, (2188-2222 ohms) The last BRN is 1%; RED, RED, BLK are 3 significant figures and BRN is a multiplier of 1 zero. Not your typical resistor.

What datasheet?

 

[KeepItSimpleStupid]

The datasheet is back in post #558 for the LM2576 : https://www.electro-tech-online.com/custompdfs/2012/06/lm2576-2.pdf

The schematic will resemble that. R1 (Datasheet) will likely be in parallel with a two (resistor and transistor (T1/T2) pair in series) on the other side of the board. The R1/R2 combo is on the other side of the board from the T1/T2 and the two resistors.

There is a bypass cap and a bridge rectifier and the component values will be slightly different than Fig 19.

The likely scenerero is that the two resistors by themselves set up one value of the output. Then one or the other or both are added in parallel using the transistors giving the possibility of 3 more values, but i suspect only two.

 

[ronv]

Rev 1.1.1.1.1.1

I added overcurrent protection and a latch to hold it. Don't know if you want to force a power cycle on failure or add a reset switch.
Also changed the sense resistor to .68 ohms and got rid of the .5 ohm in front of the regulator. Seems to run up to 25 volts or so now, although I think it would save a few watts to set the input supply at 21 or 22 volts.
Also changed the shut down from a transistor to a 2N7002. Less load on the cmos chips that drive it and a little lower voltage in shut down mode.
If you guys decide to go this way let me know and I'll do a Bill of Material at Mouser that we all can play with.

Just looking at the coil temperature numbers. Doesn't look like it would hold up to 6 amps for long either. I wonder if the controller has a shut down circuit.
Time to look closer at the chip I guess.

Joe, Do you have spice so you can see the schematics?

I hope global warming does't kill all the coral before this gets done.

 

[ronv]

Kiss,
Maybe you could hook the remaining coil to the output of the controller and see if it shuts down or just "hangs" at 6 amps? Or fuse blows? Or something?

 

[KeepItSimpleStupid]

Tough one:
1. I haven't been able to read the value on the fuse yet. It is a time delay fuse. Fuse is glass, wire leads, 4 x 11 mm. If I were to guess the rating, of the fuse, I'd say between 1 and 3 amps SB. 1.45 A = 35 VA/24 VAC. So a fuse rating of 3A SB would sound about right. Using the resistance of the fuse in circuit, It would be a 0.5 Amp fuse.
2. I initially used a (0-30 VDC) supply rated a 3 amps max. 6A is hard to come by.
3. The OEM AC supply is rated for 35 W, 240 and 240 VAC is hard to come by.

Bet the fuse would blow first. The initial 6A will come from 2000 uF of capacitance. The transformer would start to heat up and drop the voltage. I would even doubt that the regulator would go into thermal protection. 24/2.15ohm > 11 amps. I*R = 6*2.15 = 12.9V

If this is my guess, https://www.electro-tech-online.com/custompdfs/2012/06/673.pdf then at 6A, then a 3A SB fuse is liable to blow in 0.4 s.

I think I saw a 3A on the fuse. Only way to tell is remove and look, but that's what I would size it for. Note that these fuses are I^2*t rated so it would blow in 0.4 s at 6 Amps.

 

[salty joe]

Joe, Do you have spice so you can see the schematics?

Thanks for kicking this around, Ronv. I'll see about downloading spice tonight.

I hope global warming does't kill all the coral before this gets done.

That would be bad. eek. But even if all the coral on this beautiful planet croaked, I'd still keep after these pumps. I guess I must be stubborn.

By KISS "I think I saw a 3A on the fuse."

Yes, I think that's right. I'll confirm tonight.
Thanks all.

 

[ronv]

Tough one:
1. I haven't been able to read the value on the fuse yet. It is a time delay fuse. Fuse is glass, wire leads, 4 x 11 mm. If I were to guess the rating, of the fuse, I'd say between 1 and 3 amps SB. 1.45 A = 35 VA/24 VAC. So a fuse rating of 3A SB would sound about right. Using the resistance of the fuse in circuit, It would be a 0.5 Amp fuse.
2. I initially used a (0-30 VDC) supply rated a 3 amps max. 6A is hard to come by.
3. The OEM AC supply is rated for 35 W, 240 and 240 VAC is hard to come by.

Bet the fuse would blow first. The initial 6A will come from 2000 uF of capacitance. The transformer would start to heat up and drop the voltage. I would even doubt that the regulator would go into thermal protection. 24/2.15ohm > 11 amps. I*R = 6*2.15 = 12.9V

If this is my guess, https://www.electro-tech-online.com/custompdfs/2012/06/673.pdf then at 6A, then a 3A SB fuse is liable to blow in 0.4 s.

I think I saw a 3A on the fuse. Only way to tell is remove and look, but that's what I would size it for. Note that these fuses are I^2*t rated so it would blow in 0.4 s at 6 Amps.

Oh, I thought you had the standard supply. The question I was trying to answer was if the standard controller had the same problem as the one Joe built or if it had a different current limit or shut down since we know that 6 amps or worse 11 amps continious is to much.. Could be its supply limits the current to some lower value. Who knows?

 

[KeepItSimpleStupid]

Oh, I thought you had the standard supply.

I do have the standard supply. A 240 to 120 VAC 25 VA Xformer. That's what comes with it. It isn't for 120V.

The OEM controller rectifies the incoming power, so AC or DC will make it work.

With 2000 uf of filtering the supply you could sustain 2A, but the power supply is rated to 1.5A so you could only sustain 1.5A.

The question I was trying to answer was if the standard controller had the same problem as the one Joe built or if it had a different current limit or shut down since we know that 6 amps or worse 11 amps continious is to much.. Could be its supply limits the current to some lower value. Who knows?

Somewhere in this thread joe bought two 24 VDC supplies off of ebay adjustable a little., One may have been 6 and one may have been 11A.

He ran alex's controller which I believe only had slow start (limits current somewhat), and NO method for max current limiting or for that matter such as a 3A fuse per pump. Joe had 4 pumps running in pairs on a single high current supply.

Hence: The pump let out the magic smoke.

Some of the conclusions were:

The OEM controller has a 3-6A current limit (regulator), has a fuse which is probably 3A and has a transformer which is rated for 35 VA. The OEM controller is known to have problems (regulator dies) as well. I believe they are: No diodes for back EMF, no diodes to jump the regulator, Poor selection of output caps (not high ripple). This controller has changes to earlier earlier controllers of a fuse and better inductors per pics on the net.

The conclusions are guesses at best:

Joe believes the OEM controller has issues but he believes the pumps are sound. I confirmed regulator failures on the net. I confirmed some changes (better inductors and fuses). The OEM controller operates nowhere near 100% at 24/7. I still think the OEM controller has minor issues that 2 diodes and a capacitor replacement would fix.

The pump seems flakey due to the possibility of no spike or locked rotor protection (unless the fuse works) so we have three choices: 1) Do the best we can externally to protect the pumps or 2) Re-design the pump internals by stripping away the epoxy. 3) Both.

2.5 A is a good number that the winding wire could survive easily in water.

Then there was the solder blob....

 

[ronv]

I do have the standard supply. A 240 to 120 VAC 25 VA Xformer. That's what comes with it. It isn't for 120V.

Missed that.

The OEM controller rectifies the incoming power, so AC or DC will make it work.

Ok. so we would need a bigger supply to make it work. I get it now. I thought you were using the stock controller.

With 2000 uf of filtering the supply you could sustain 2A, but the power supply is rated to 1.5A so you could only sustain 1.5A.

It has to get the current from somewhere to ever blow the fuse. I suspose the teansformer could drop to 12 volts under a 6 amp load then it would blow in 10 seconds. If its really a 3 amp fuse)

The OEM controller has a 3-6A current limit (regulator), has a fuse which is probably 3A and has a transformer which is rated for 35 VA. The OEM controller is known to have problems (regulator dies) as well. I believe they are: No diodes for back EMF, do diodes to jump the regulator, Poor selection of output caps (not high ripple). This controller has changes to earlier earlier controllers of a fuse and better inductors per pics on the net.

OK

Then there was the solder blob....

That one doesn't susprise me. With the big supply the FET would get hot enough to melt it as well as the coil.

Here is my take on the failure:

The pump FETs have protection from the inductive kick either thru protection in the FET or they are avalance rated for enough current. Without that they would pop in nothing flat.

It could have been a bad part (FET or Hall) but with only 3 active components I would really be suprised that 1 in 100,000 would ever fail in our lifetime.

A mechanical failure - bind in the bearings or pump - this is my favorite.

Perhaps the solder blob moved enough to cause a short. I'll go back and look some more at the pictures.

Maybe being a 2 pole pump it just fails to start sometimes. Again, I think a long shot.

One thing is clear. Both the FET and the coil will fail on the big supply with no current limit and shutdown should it ever stall.

I guess I'm not convinced the stock controller is any better than the Alec supply without knowing more about it.

 

[KeepItSimpleStupid]

One thing is clear. Both the FET and the coil will fail on the big supply with no current limit and shutdown should it ever stall.

Agreed 100%. That is about all we know for sure.

The OEM controller rectifies the incoming power, so AC or DC will make it work.

It rectifies the 24 VAC from the transformer.

I guess I'm not convinced the stock controller is any better than the Alec supply without knowing more about it.

It's limited in power delivery: 3 A fuse on 24 VAC side; 35 VA transformer; 2000 uf filtering (off the rectified 24 VAC); switching regulator current limits; Ripple filter; slow ramping starts (possibly a no load effect) The pumps are VERY CHEAP compared to Tunzies like a factor of 20.

One of the "test cases" I was recommending was to use an OEM controller at a "some fixed voltage" with his 24 VDC supply and just operate a pump continuously. For giggles, one could put a temp sensor on the outside of the pump and stop the test at some external temp. This would answer the question, "Can the OEM controller run a pump 24/7"?

This could probably be done by pulling T1(TR1) and T2(TR2) and inserting a single jumper or a POT. My problem once we know the circuit composed of the 4 resistors and 2 transistors. We could also add the three suggested mods my me, 2 diodes and a better output cap.

But, we have a higher risk of loosing a pump than if other protections are incorporated.

It cannot sustain 35 VA continuously, not can it sustain (3A * 24) or 75 W for more than about 0.4 seconds. Peak currents will be surpressed by the regulator.

Alex's circuit/power supply could. (supply max current - 1 operating pump) , so if a 6A supply; 5*24 or 125 W was available for the BBQ. If 11 A, then 10*24 or 240 W was available for the BBQ. Assumes an operating pump draws 1 Amp. 1.5 might be closer.

Looks mostly textbook out of the application notes with Vset being a fixed divider and two other resistors could be placed in parallel with one of the fixed resistors to change the voltage to 3 separate values. The ramping I saw may be related to running without a load.

The most damage would be 24*24/2.15 or 267 W per coil, 2X that or 534 W if they were both on and if the power supply could supply it and there was no other resistances in the circuit. There is definitely meltdown possibilities.

One thing we never through out was if another pump was spinning the pump wanting to start backwards through water currents?

Remember, again Joe wants two "pump systems" 1) A Wave controller and 2) a tide controller

The "Wave Controller" is for the corral to create lots of water movement. Think slosh the tank at resonance. Two pumps alternate against one another to make waves. The sleepy pumps gets "woken up" once in a while to shoo the fish.

The "tide controller" is less understood by me, but the period is longer and the unused pump gets woken up once in a while to "shoo the fish".

So, Joe needs a bigger supply that can run at least 3 pumps simultaneously and to start 2 or three briefly (The flick) to shoo the fish.
There was talk of a tide power supply and a wave power supply.

alec knew nothing about the OEM controller/power supply/motor when he started. All he really knew was 24 VDC motors and possibly 35 VA.

 

[ronv]

Avalanch mode

I did a couple of sims with the motor running at 6 amps (start up current) and another at 1.3 amps (running current).

I don't know what to say about the start up current as it decreases with time, but the first commutation calculates at about 110 mj if we assume the FET to be in avalnch mode to supress the inductive kick. This is within the single pulse rating (50%). Like I said I don't know how to simulate the entire start up because the duty cycle and current change. I did another at 1.3 amps and it comes out 6 mj which is about 50% of the repetitive rating. So all is cool there. The power at 1.3 amps in the FET during avalanch is 25 watts X 1% duty cycle or .25 watts. Not a problem.
In checking for spikes I don't see any. The simulation is not the best in the real world but it does say this may be how it works. I wouldn't want to cycle it at .5 seconds on and .5 seconds off that's for sure.

 

[ronv]

Start up

Here is the last sim of a start up. Takes forever to run on my poor old computer.
I also made the timeout for over current shorter per Alec's post. (~.7 seconds?)

Time for my nap. It's Arizona you know.

 

[KeepItSimpleStupid]

I wouldn't want to cycle it at .5 seconds on and .5 seconds off that's for sure.

100% agreed again.

Would it make any sense for joe to send me a working pump? I do have a scope, but it's not a DSO. Not sure if I can dig up a shunt.

As I said I do have a 50 lb 10 A, 32 V supply with foldback current limit, but it would need to be re-configured internally. A short on this supply drops the voltage to nearly zero. Basically similar to this beast: **broken link removed**

 

[alec_t]

Gosh, you guys have been busy with posts while I've been away for a while. I'm still working on a couple of sims for coping with the main current-hogging bit....rotor lock. One uses a LM1084 and the other uses a LM2576 (as per the OEM controller). Will post when done.

 

[KeepItSimpleStupid]

The values of the programming resistors from the cord side to the opposite side are:
R R Blk R Brn 22K = R1
Or Blk Blk Br Br = 3K

Grn Red Blk Br Br = 5210 near T3 or TR3
Red Red Blk Br Br = 2255 nearT2

So Vout = 1.23 * (1+R2/R1) R2 = 22K

so, if T1 and T2 were turned off, R1 would equal 3K and Vout = 10.25 Volts (10 was measured)

If T2 was turned on, then R1 = 3K||5210 or and Vout = 18.7 V (15 was measured) so that resistor could be a 6210 Grey vs Green. That would calculate to 14.6 Volts.

If T3 was turned on, then R2 = 3K||2200 and Vout would equal 22.5 V (22.6 was measured)

So, if you pulled the 5210 resistor and the 2200 resistor (lift a leg) and put a 1K in series with a 5K pot where the 3K resistor was (or, blk, blk, blk, brn) you would have an adjustable supply from 5.74 to 28.29 volts.

If you wanted to permanently turn it into an adustible supply, you could probably do some surgery around T2/T3 and put a 10-turn trimmer potentiometer in one of the transistor positions, hopefully.

@Joe
What colors do you get for the resistors near T1 and T2?

That makes most of the High voltage schematic pretty easy. I just need at least one inductor value.

 

[salty joe]

There are 3 resitors near T1 and they have a tan body with 4 stripes. The stripes are brown, black, red, gold and brown, green, green, gold and yellow, blue, red, gold.

There are 2 resitors near T2 and they have a lime green body with 5 stripes. The stripes are brown, brown, black, red, red and blue, red, black, brown, brown.

The fuse is 3A 250V.

 

[KeepItSimpleStupid]

Your blue makes sense. Makes the 5210 a 6210. My other colors and values appear to be right.