Help with Water Pump

[KeepItSimpleStupid]

Just my 2 cents:

I think the pump voltage is ok as is because:
1- The lable on the pump states 24 volts.
2- The OEM controller had higher voltage than the current supply
3- The hall IC shows a 24 volt implentation.

I only have 2 thoughts on the original failure:

1- A stall with no current limit other than the motor winding resistance. (200 watts for 1 second is to much)
2- Manufacturing defect.

Joe, Are you up and running now? Or do you still have the alarm bug?

1. Don't know. I haven't seen a pump, but the label on the wall wart says 24 VAC.

2. Disagree. The OEM controller operated very briefly at a higher voltage (22.6 V). It did not reach 24 VDC. The OEM had current limiting based on the switching regulator My notes say 11 s ramping to 11V, 10 sec raping to 19 V and 4 sec ramping to 22.6 V using maximum times, then ramping back down to 11 V.

3. Agree

____

1. Agree. Joe said he had a 3 A fuse, but it did not blow. This makes no sense.
2. Agree. The solder blob near the FET is very suspicious and could have very well been a manufacturing defect. In a scenereo where the motor tested fine, but when it got hot, the solder blob touched the FET.
There is no protection offered by the Hall IC at that point.

What's your take on a 3A fuse blowing on a Locked Rotor Condition? I doubt it would blow.

 

[salty joe]

The alarm bug was me not finishing the IC work. Once pins 4, 8 and 9 were tied together and 12 & 13 grounded, the alarm worked like a champ. So yes, there is a pair of PDMs that work real well.

Since you guys believe 20V seems reasonably safe, that's it.

I want to start making more PDMs but don't want to jump the gun again. This PDM version looks good to me, do you agree?

Since the tank filter is at same level as the tank, (this type pump has virtually no ability to lift water, but they move a lot of water using little electricity) I am using another pair of pumps to move water through the filter. This will be the only pair with speed control. The current pair of PDMs has terminals for speed, prolong, and Isense. Isense and speed hooks from both PDMs are tied together and the prolong hooks are separate. So two PDMs, one terminal for speed, one terminal for Isense and two terminals for prolong. Is that right? Also, this pair of pumps will run nonstop. Do the PDMs for this pair need to be modified?

 

[ronv]

KISS, This is where I got the info.

Fuse size and current:
https://www.electro-tech-online.com/threads/help-with-water-pump.124250/#post1061197
Pump picture:
**broken link removed**
OEM voltage:
SMALL ramps down the voltage from 22.6 to 17.1 VDC over probably 10-30 s (I didn't measure it carefully)
MIDDLE ramps the voltage from 17.1 to 14.9 over probably 10-30 sec (I didn't measure it carefully)
BIG goes directly to 22.6 volts

Joe,
I'm not sure we have info on prolong and speed control, but the only hole I see is if Vth is just tied high on the pumps that run all the time the timeout for the alarm will be shorter for the second try. This may be what prolong is for?

Glad they are working now!

 

[alec_t]

one terminal for Isense and two terminals for prolong. Is that right?

The two Isense lines should also go to separate terminals, as should the two SpeedCon lines, even if two pumps are paired.

Also, this pair of pumps will run nonstop. Do the PDMs for this pair need to be modified?

As Ronv points out above, "if Vt is just tied high on the pumps that run all the time the timeout for the alarm will be shorter for the second try." This could also happen if a rotor stuck during pump toggling. To avoid that timing difference we could reinstate a couple of resistors and a diode that were present in an earlier incarnation. Or could you live with the initial timeout period being ~ twice subsequent timeout periods (which admittedly makes setting the trimmer correctly a bit harder)?

This may be what prolong is for?

'Prolong' is for use in conjunction with the proposed speed control, to prolong the timeout period to compensate for the coil current pulses being longer when the motor is rotating more slowly.

 

[ronv]

Maybe we should just stall the pump by hand once and see if the hall sensor shuts it off. If it does the alarm won't matter so much. It might also be useful to know, as if it does shut it off, it may impact the speed control?

 

[alec_t]

if it does shut it off, it may impact the speed control?

Don't think it will affect the speed control, but I'll try to run a sim tomorrow.

 

[KeepItSimpleStupid]

Joe:

As I suggested earlier, Isense and the bottom of the 0.22 resistor SHOULD be brought out to real terminals as TEST POINTS. To re-iterate, terminals should be used to be able to measure the voltage across the 0.22 ohm resistor.

Measure this voltage and the voltage between pump- and pump+ before starting your long term testing.

Be sure the motor is running.

 

[ronv]

Yea, I think your right. After reading your article again it seems good to go.

 

[salty joe]

The two Isense lines should also go to separate terminals, as should the two SpeedCon lines, even if two pumps are paired.
As Ronv points out above, "if Vt is just tied high on the pumps that run all the time the timeout for the alarm will be shorter for the second try." This could also happen if a rotor stuck during pump toggling. To avoid that timing difference we could reinstate a couple of resistors and a diode that were present in an earlier incarnation. Or could you live with the initial timeout period being ~ twice subsequent timeout periods (which admittedly makes setting the trimmer correctly a bit harder)?
'Prolong' is for use in conjunction with the proposed speed control, to prolong the timeout period to compensate for the coil current pulses being longer when the motor is rotating more slowly.

I’ll separate Isense and speed, just like the prolong hooks. Thanks.
If I pushed the trip test a couple times forcing the PDM into alarm mode a couple times, would that make adjusting the trimmer easy?
Does Vt tied high mean connecting Vt to 12V?

Joe:

As I suggested earlier, Isense and the bottom of the 0.22 resistor SHOULD be brought out to real terminals as TEST POINTS. To re-iterate, terminals should be used to be able to measure the voltage across the 0.22 ohm resistor.

Measure this voltage and the voltage between pump- and pump+ before starting your long term testing.

Be sure the motor is running.

I’m still not sure of the enclosure for the boards, but I will most definitely bring those four points out for every PDM. I’ll also label every pump and record the numbers in the tank log. Thanks.

 

[KeepItSimpleStupid]

Joe:

Here is a little "cartoon" to look at. It "essentially" shows how control panels are constructed. No wiring and I don't see any wiring duct. You might be able to build one out of wood or some combination of wood and metal. https://jansson.us/EbreweryModel.html

Look here at the pic entitled "Custom controls by GPI..." at the bottom for another DIN rail technique.
**broken link removed**

And here is an Elevator controller using wiring duct, and DIN terminals at the bottom.
https://www.electro-tech-online.com/custompdfs/2012/11/wissam20elevator20m.pdf

You can see where metal has it's advantages for fire etc.

 

[salty joe]

Thanks for the ideas and pictures. The tricky part is mounting them very close to the tank without blocking access to the tank.
Do all six sides of the enclosure need to be lined in metal to act as a Faraday cage?

 

[KeepItSimpleStupid]

The frequencies are so low at least for your circuits, that it probably doesn't matter.

The switching power supplies probably have their own cover which should be attached to Earth.

The radiators of any RFI will likely be the motor cables themselves.

I was only thinking metal (i.e. Steel or aluminum) for ease of mounting switches and cord glands and any "Front panel" that you might want to have and they could be sporadic.

I also thought of maybe using a light gauge of aluminum or steel for fire protection. A real cabinet is very expensive, but they can be built to withstand being outside. There are protection levels assigned to various enclosures: https://en.wikipedia.org/wiki/IP_Code

I thought the tank is sort of in the garage, so if you had room on any side, that could be for any controls. Maybe even ones you havn't thought of yet. e.g. fish feeders, UPS, backup pumps, lighting controllers, PH/ORP controllers, filter clog alarms, humans putting fingerprints on the glass alarms, temperature displays, whatever.

No, your not there yet, but a lot of times the case is sometimes considered first. That was also why I wanted you to consider the Snap Trac form factor.

As I said earlier, the case, power supply and real estate (the PCB itself w/o components) are the major costs in a PCB project.

You really don't need the controllers close to the tank, but yep, it would be nice if the cords of the pumps reached the controller. If you did extend them, I'd consider a larger wire gage of shielded cable inside of PVC conduit.

The shield only gets connected at one end to ground and that would provide RFI protection. The PVC would protect against the salty environment.

 

[alec_t]

I ran the sim. Because the speed control is synchronous with the Hall IC switching there is no adverse interaction if the IC decides to shut down with a stuck rotor.

If I pushed the trip test a couple times forcing the PDM into alarm mode a couple times, would that make adjusting the trimmer easy?

With the toggle 'on' and 'off' times set to max and a pump running, push the test once to cause the initial trip. The trimmer would then need to be set such that the pump re-starts reliably when the trip-timer resets after ~30s. (If the trimmer is set at too low a value the pump won't have enough time to get up to speed and the trip will be triggered again).

Does Vt tied high mean connecting Vt to 12V?

Yes.

On a different note, since your system is 24/7/365 would it be worth adding the feature of actuating an alarm if a pump stopped running for a reason other than stuck rotor, e.g if the pump motor went open-circuit? If so, it should be a straightforward (famous last words ) mod of the speed control module, or perhaps a small add-on module per PDM, but another hook should be added to your (as yet unbuilt) PDMs to allow for it. I'll mod the schematic to show what I mean (and incorporate the mods to date) and post it as Mk15.

Edit: Time for bed. Will post tomorrow.

 

[salty joe]

Tripping the pump on the nonstop PDM before setting the trimmer sounds like a plan.

If a stopped pump alarm built into the PDMs is not a big deal for you to do, I'd be all for it. Built into the PDM would be better because speed control will only be on the pair of pumps that will run nonstop.

A brand new clean and shiny schematic would be very much appreciiated. Thanks and sleep tight. I'm hittin the rack too.

 

[salty joe]

You really don't need the controllers close to the tank, but yep, it would be nice if the cords of the pumps reached the controller. If you did extend them, I'd consider a larger wire gage of shielded cable inside of PVC conduit.

The shield only gets connected at one end to ground and that would provide RFI protection. The PVC would protect against the salty environment.

I like that idea a lot-thanks. The terminal blocks I'm using can hold 14g wire. If the pump leads could be extended another 12-15 feet, all the electronics could be out of the fish room. That would be nice because everthing in the fish room is a tight fit and no worries with humidity and electronics.

 

[KeepItSimpleStupid]

I like that idea a lot-thanks. The terminal blocks I'm using can hold 14g wire. If the pump leads could be extended another 12-15 feet, all the electronics could be out of the fish room. That would be nice because everything in the fish room is a tight fit and no worries with humidity and electronics.

I don't see issues with that.

If a stopped pump alarm built into the PDMs is not a big deal for you to do, I'd be all for it. Built into the PDM would be better because speed control will only be on the pair of pumps that will run nonstop.

I'm missing something here. Isn't speed control is also required for feed mode?

 

[alec_t]

Here's the Mk15 schematic. I'm still working on the fault sensor add-on. Thought I had it sussed, but a sim proved otherwise Changes from the Mk14 are highlighted with dotted rectangles.
View attachment 68756
Note the added D10/D11 and different connection of U1d to provide a hook for the fault sensor if used.

Edit: R11/R12/D9 help to equalise the trip times. The first trip delay is now only ~20% longer than subsequent delays.

 

[salty joe]

I'm missing something here. Isn't speed control is also required for feed mode?

I will only use feed mode on one pair of pumps that pull water past the overflow and through the filter. Food getting bounced around the tank is good-food going to the filter is not so good.

Here's the Mk15 schematic. I'm still working on the fault sensor add-on. Thought I had it sussed, but a sim proved otherwise Changes from the Mk14 are highlighted with dotted rectangles.
View attachment 68756
Note the added D10/D11 and different connection of U1d to provide a hook for the fault sensor if used.

Edit: R11/R12/D9 help to equalise the trip times. The first trip delay is now only ~20% longer than subsequent delays.

Thanks Alec-that's a nice looking schematic. Now that I think all the electronics are going to be in a closet in the basement, I'd like to mount the alarms on the wall outside the closet. Would the alarms likely work if I used about 6 feet of 19G wire?

 

[KeepItSimpleStupid]

Would the alarms likely work if I used about 6 feet of 19G wire?

Don't see a problem with that.

@alec

Has the "alarm module" been designed yet?

I somehow would think of a single buzzer with an alarm silence switch and a Trouble light which would be similar to a fire alarm system. Then indicators for the various pumps/alarms.

A possible suggestion: a Bi-color LED that illuminates RED if in alarm and GREEN when actually running.

Now with locked rotor, not running being alarm conditions they could be indicated by RED and YELLOW. Actually running can be green.

I know that when designing computer interfaces there is a lot of "show me something" and I'll make changes. It might be the same thing here.

There isn't a "design specification" that we started with, but rather touch and go.

Frankly, I'm loosing count of the number of pumps already. I thought there was a tide controller, a wave controller which was 6 pumps) and now two pumps that just run. So, is that 8 pumps now?

At the rate your going, you won't have any room for fish?

 

[salty joe]

Yes, eight pumps. Six on controllers to keep things moving in the tank and two to run nonstop with a feed mode to circulate water through the filter. I plan to use both power supplies at 20V. The power supplies are rated at 15A.