480 volt motor

[meternerd]

What would be wrong with swapping them in the disconnect. None of the ungrounded conductors are identified color wise. I figured it would be the better option because after each contactor every connection is numbered. The second winding starts two seconds after start

Did you read my post above yours? If conductors are not color coded brn org yel ABC or numbered, they should be. Doing it at the disconnect means that on top of the disconnect you may have ABC CW, but at the load connected to the bottom (top of contactor), you swapped wires and now have ACB CCW. If everything you work on is clockwise, then life is much simpler. What if your contactor is CW, but the one for the motor next to it is CCW? If you have only one 3 phase load, it doesn't matter, but that's not usually the case. You may have conveyors, fans, other pumps, etc. that are wired to the same source. If you swap yours at the disconnect, it may end up CW at the contactor. Now the next device may be CCW at the contactor because that guy decided to swap his rotation the same way you did. Now poor old electrician ME comes along, disconnects the motor but forgets to write down how it was connected. Well...50/50 chance, right? On many pumps, such as shaft driven turbine pumps that may have 500' of shaft between the motor and the pump, reverse rotation can unscrew the shaft couplings and you'll find yourself with a pump at the bottom of a well that has no way to be recovered. These types are removed by pulling them up by the shaft. Others have seals that will be destroyed if run in reverse. That said....my background is in the utility industry, both electric generation and water. I was taught that you always wire motor circuits ABC clockwise all the way to the bottom of the starter. Rotation is wired at the motor. That way, any work requiring disconnection of anything ahead of the motor can always be hooked back up correctly. Just the way I've been doing it for more years than I care to count. I understand that you can reverse rotation anywhere you have all three phases, but why not make it easy on everybody? Just kidding about yelling at you though. I'll just stomp away and pout, or "rat you out" to the boss.

 

[Jraef]

... Something happened that scared the living shit out of me as the pump was shut down, water hammer. The hole platform, motor and pump and piping system jumped violently as the pump stopped. I have no idea why it never happened before it was rewound. We had a hydrant open and a new check valve was installed. As long as it's not electrical it's not my problem.

Well, hold on. In many cases, there MIGHT have been an 'electrical" solution to the water hammer issue, and in all the work you did, you may have inadvertently left it unconnected. A common way of protecting against water hammer is to use what is called a "pump control valve". The way it works is that when you give the pump a normal "Stop" command, i.e. a float or pressure switch, stop button etc., it doesn't actually stop the pump immediately. The Stop command actually goes to the pump control valve to release a solenoid, which slowly closes the valve hydraulically (using the water pressure). Then when the valve gets to its end of travel when closed, it opens up a limit switch and the LIMIT switch then kills the starter coil power to shut it down. If, in your rework, you failed to connect that system back up correctly, you may be killing power to the contactor coils too early, which is making the valve slam closed. If that happens too much and damages a pipe or the pump, and someone later discovers it WAS an "electrical problem", they might hold you responsible for the damages.

But if you witneseds the water hammer take place as a result of you having thrown the disconnect switch as opposed to a normal shut-down, that would do it too, which just means you essentially bypassed the regular system that one time, so don't worry about it.

 

[meternerd]

Well, hold on. In many cases, there MIGHT have been an 'electrical" solution to the water hammer issue, and in all the work you did, you may have inadvertently left it unconnected. A common way of protecting against water hammer is to use what is called a "pump control valve". The way it works is that when you give the pump a normal "Stop" command, i.e. a float or pressure switch, stop button etc., it doesn't actually stop the pump immediately. The Stop command actually goes to the pump control valve to release a solenoid, which slowly closes the valve hydraulically (using the water pressure). Then when the valve gets to its end of travel when closed, it opens up a limit switch and the LIMIT switch then kills the starter coil power to shut it down. If, in your rework, you failed to connect that system back up correctly, you may be killing power to the contactor coils too early, which is making the valve slam closed. If that happens too much and damages a pipe or the pump, and someone later discovers it WAS an "electrical problem", they might hold you responsible for the damages.

But if you witneseds the water hammer take place as a result of you having thrown the disconnect switch as opposed to a normal shut-down, that would do it too, which just means you essentially bypassed the regular system that one time, so don't worry about it.

Zactly! All of our booster pumps that pump from one elevation to another have this setup. Cla-Val is the major supplier. But, those systems don't usually have a check valve for the very reason stated. Water hammer. If you turn off a disconnect or have a power outage, the pump stops and the valve begins to close, but the pump will spin backward while this is happening. Much less impact on piping than hammer. Many of our pump motors have ratchets which prevent reverse rotation, which is even better. The biggest danger is starting a motor with the valve open. Normally the motor starts, then the valve slowly opens. No hammer. If you override the sequence and let the motor start while the valve is open, the resulting "slug" of water can blow pipes completely out of the ground. Don't ask me how I know.....! Oops!

 

[Jraef]

Zactly! All of our booster pumps that pump from one elevation to another have this setup. Cla-Val is the major supplier. But, those systems don't usually have a check valve for the very reason stated. Water hammer. If you turn off a disconnect or have a power outage, the pump stops and the valve begins to close, but the pump will spin backward while this is happening. Much less impact on piping than hammer. Many of our pump motors have ratchets which prevent reverse rotation, which is even better. The biggest danger is starting a motor with the valve open. Normally the motor starts, then the valve slowly opens. No hammer. If you override the sequence and let the motor start while the valve is open, the resulting "slug" of water can blow pipes completely out of the ground. Don't ask me how I know.....! Oops!

Yep, Cla-Val work fail safe like that, but not all of them do. Don't ask me how I KNOW either... :weeping:

 

[kwired]

Yup...likely a part winding start. Easy to hook up. Both starters have the line side connected to the same breaker. Most times, they wire to the first starter then jumper over to the second. As long as the phases are the same on the top side of the starter, they will be the same on the load side. To test rotation without a meter, just disconnect the motor leads from one or the other starter and give it a quick bump. Then do the same on the second starter. A quick bump on a part winding is not a problem. Just see that they both rotate in the desired direction. Motor leads are usually labeled with the first winding 1, 2, 3. Second may be 4, 5, 6 or 7, 8, 9. If in doubt about windings, do a continuity check between wires. Winding one will read low ohms between leads. Winding two will read the same. Winding one will not read to winding two. They're separate. If you have some other motor such as multi-voltage or star/delta, they are different. Be careful.

We have many pump stations with three of four pumps. One pet peeve of mine is finding someone reversing rotation at the starter. In my opinion, that's a headache. Phase sequence should be clockwise at the starter ABC, Brown Orange Yellow, left to right or top to bottom. Then, if you want reverse rotation at the motor, reverse the leads at the motor, not at the starter. Write the colors BOY or BYO inside the cover, so you'll always know. That way, any time you disconnect motor leads, you'll always know that it's Brown, Orange, Yellow Left to right. That's my opinion. If yours is different I'll loudly explain why you're wrong.

Have you ever had to climb 150 - 200 feet of grain elevator leg just to reverse rotation of the motor? Much, much easier at the controller sometimes and takes only a few minutes instead of most of an hour.

 

[ActionDave]

Have you ever had to climb 150 - 200 feet of grain elevator leg just to reverse rotation of the motor?....

or the exhaust fan at the top of the gable in the shop at the same farm, or at the top of a conveyor at the gravel pit, or behind a safety fence under the concrete batcher, or in a below grade sewer lift station, or on top of the bailer at single stream recycle plant, or maybe because the leads at the pecker head are already made up with split bolts and tape...

 

[meternerd]

Would it destroy the elevator if it was wrong? I think we're talking elevators vs. pumps or other such multiple loads off of the same service. Always exceptions to any rule, but in my experience, my way eliminates the extreme danger of reverse rotation when you're in the middle of an outage and THEY are breathing down your neck to get it fixed. Plus, I'm not the only electrician, so the other guy (or guys) may not know exactly what the guy before 'em did last. When you work in a place such as a nuclear plant that has hundreds of three phase motors, you have to have a system. That's mine. Yours is whatever works for you.

Have a gidday!

 

[meternerd]

or the exhaust fan at the top of the gable in the shop at the same farm, or at the top of a conveyor at the gravel pit, or behind a safety fence under the concrete batcher, or in a below grade sewer lift station, or on top of the bailer at single stream recycle plant, or maybe because the leads at the pecker head are already made up with split bolts and tape...

Welcome to the world I lived in. Didn't matter...split bolts, medium voltage 13,800V with stress cones, etc. Always done the same way. Never been a lone ranger electrician though. Only utility work. Different issues for sure.

 

[stevenbouf]

Ok I get what your saying meternerd. There's only two pumps at this location and they each have there own disconnect before there control panels. There isn't any others controls besides the two contactors and the timers, the motors where only started and stopped with the stop start station nothing was unhooked besides the motor leads and the two wires swapped in the disconnect. The only thing I see that changed is a check valve directly after the pump. That's not part of my job. It's piped as follows, foot valve 20 feet 8-10 inch pipe into pump out of pump directly into a check valve into a length of pipe with some type of air vent and over pressure valve (that doesn't work) than splits to multiple lines to hydrants that the farmers connect to them big sprinklers that spand the length of the field that drives.

 

[stevenbouf]

Welcome to the world I lived in. Didn't matter...split bolts, medium voltage 13,800V with stress cones, etc. Always done the same way. Never been a lone ranger electrician though. Only utility work. Different issues for sure.

This motor has crimped hoop connectors on field wires and motor leads that are nut and bolted than cantex tape than rubber that electric tape. So I didn't want to take all that apart again.

 

[meternerd]

Ok I get what your saying meternerd. There's only two pumps at this location and they each have there own disconnect before there control panels. There isn't any others controls besides the two contactors and the timers, the motors where only started and stopped with the stop start station nothing was unhooked besides the motor leads and the two wires swapped in the disconnect. The only thing I see that changed is a check valve directly after the pump. That's not part of my job. It's piped as follows, foot valve 20 feet 8-10 inch pipe into pump out of pump directly into a check valve into a length of pipe with some type of air vent and over pressure valve (that doesn't work) than splits to multiple lines to hydrants that the farmers connect to them big sprinklers that spand the length of the field that drives.

That's what check valves do. They prevent backflow by slamming shut. The higher the differential pressure, the harder they slam. Sounds scary, but probably not dangerous.

Same reasoning....motor controls should both be exactly the same up to the motor. Any rotation changes should be done at the motor. But, the dead horse is now REALLY dead...Bye!:bye:

 

[GoldDigger]

Out here where open ditch irrigation and flood irrigation are common you will often see a 6' high concrete pipe, open at the top. next to the gate valve.
It is essentially a pressure relief valve for the low pressure pipe system. Shut off the valve and the water rises out of the top of the pipe until the kinetic energy of the moving water upstream of the valve has been dissipated.
Does not work really well for a pressurized system.

 

[stevenbouf]

Out here where open ditch irrigation and flood irrigation are common you will often see a 6' high concrete pipe, open at the top. next to the gate valve.
It is essentially a pressure relief valve for the low pressure pipe system. Shut off the valve and the water rises out of the top of the pipe until the kinetic energy of the moving water upstream of the valve has been dissipated.
Does not work really well for a pressurized system.

That sounds like a good idea. I'm not sure if this system was engineered. I suspect it's that new check valve is the problem. Maybe it's in backwards lol. There gonna get someone to look at it. Thanks for all the replies all the other pumps on the farm have a vfd type starting system.

 

[kwired]

Welcome to the world I lived in. Didn't matter...split bolts, medium voltage 13,800V with stress cones, etc. Always done the same way. Never been a lone ranger electrician though. Only utility work. Different issues for sure.

The utility guys don't have to change direction of those items at the motor. All they do is check rotation at the service before energizing any time they have done anything that may have changed it.

I do recall one time where they did check rotation and had it right - but for some reason forgot to make sure the high leg of that system was in the right position - was not good.

 

[meternerd]

The utility guys don't have to change direction of those items at the motor. All they do is check rotation at the service before energizing any time they have done anything that may have changed it.

I do recall one time where they did check rotation and had it right - but for some reason forgot to make sure the high leg of that system was in the right position - was not good.

True....we try to set new services ABC clockwise at the service. That way, when we have any wiring changes, we know how to put it back. For existing services, we do check, just in case. 240 4W services are mostly long gone, so no problem there. I was talking about water, though. We are also the water utility, so it's the way I set it up when I got here (17 years ago). Before, they just did whatever was easy. Kind of a setup for the next guy who had to do repairs. When I first got here, I was called to a site where our linemen had seen a 120/208 service with BK RD BU WH colored wires marked with tape, but since the black was not taped (wire was already black), they assumed it was the neutral. Energized it and had 120 on the neutral all night long. No smoke. Amazing. I don't remember, but it must not have been bonded yet.

 

[kwired]

True....we try to set new services ABC clockwise at the service. That way, when we have any wiring changes, we know how to put it back. For existing services, we do check, just in case. 240 4W services are mostly long gone, so no problem there. I was talking about water, though. We are also the water utility, so it's the way I set it up when I got here (17 years ago). Before, they just did whatever was easy. Kind of a setup for the next guy who had to do repairs. When I first got here, I was called to a site where our linemen had seen a 120/208 service with BK RD BU WH colored wires marked with tape, but since the black was not taped (wire was already black), they assumed it was the neutral. Energized it and had 120 on the neutral all night long. No smoke. Amazing. I don't remember, but it must not have been bonded yet.

Linemen are easily confused by white tape as the rotation tester has red/white/blue leads:happyyes:

I see many of them mark an ungrounded conductor with white tape as that is where the white lead needed to go when testing rotation.

 

[gadfly56]

Zactly! All of our booster pumps that pump from one elevation to another have this setup. Cla-Val is the major supplier. But, those systems don't usually have a check valve for the very reason stated. Water hammer. If you turn off a disconnect or have a power outage, the pump stops and the valve begins to close, but the pump will spin backward while this is happening. Much less impact on piping than hammer. Many of our pump motors have ratchets which prevent reverse rotation, which is even better. The biggest danger is starting a motor with the valve open. Normally the motor starts, then the valve slowly opens. No hammer. If you override the sequence and let the motor start while the valve is open, the resulting "slug" of water can blow pipes completely out of the ground. Don't ask me how I know.....! Oops!

To the best of my knowledge, this doesn't result in the classic water hammer. Water hammer is induced by CLOSING a valve too quickly, not by having one open. The hammer effect is the result of the moving water causing a low pressure area in part of the piping system. The pressure gets so low that the water boils at ambient temperature, forming a vapor void. That void acts like a spring, slowing down the water until it slams back to collapse the void.

When you are filling a pipe system, the velocity of the water can be very high at the water/air interface. When the water/air interface changes direction, as at an elbow, there can be a tremendous momentum change, much higher than if the pipe was completely filled with water.

 

[Jraef]

To the best of my knowledge, this doesn't result in the classic water hammer. Water hammer is induced by CLOSING a valve too quickly, not by having one open. The hammer effect is the result of the moving water causing a low pressure area in part of the piping system. The pressure gets so low that the water boils at ambient temperature, forming a vapor void. That void acts like a spring, slowing down the water until it slams back to collapse the void.

When you are filling a pipe system, the velocity of the water can be very high at the water/air interface. When the water/air interface changes direction, as at an elbow, there can be a tremendous momentum change, much higher than if the pipe was completely filled with water.

I was taught that what we call "water hammer" is actually a shock wave that is the result of the kinetic energy represented by the fluid velocity being trapped in the closed system of the piping when there is a sudden change in that velocity, so it can happen on stopping when a check valve slams closed, or starting (albeit less often) of flow too quickly. Water cannot compress, so that kinetic energy becomes a pressure (mechanical) shock wave, traveling up and down the pipe looking for the weakest link in which to dissipate. That is why you can get rid of it in your household water pipe systems by simply trapping some air in a sealed vertical pipe, because having the air allows for a compression-able element in the system to absorb the kinetic energy. On larger systems a trapped air system becomes more unwieldy, but I have seen them ("surge tanks") that consist of room-sized concrete chambers under ground with controlled ventilation that allows for a specific maximum velocity change, whether from stopping or starting. Doing it with the pump control valves is just a different method of dealing with the same issue.

 

[meternerd]

To the best of my knowledge, this doesn't result in the classic water hammer. Water hammer is induced by CLOSING a valve too quickly, not by having one open. The hammer effect is the result of the moving water causing a low pressure area in part of the piping system. The pressure gets so low that the water boils at ambient temperature, forming a vapor void. That void acts like a spring, slowing down the water until it slams back to collapse the void.

When you are filling a pipe system, the velocity of the water can be very high at the water/air interface. When the water/air interface changes direction, as at an elbow, there can be a tremendous momentum change, much higher than if the pipe was completely filled with water.

OK...we're talking plumbing, not electrical, but I think terminology is the issue here. If you get a pressure "spike" for whatever reason, it can damage piping, instrumentation, or the poor customer's shower experience. None are good. Hydraulics 101. Smooth and slow. Oh..wait, that was the way I used to work! No wonder they were glad I retired!

 

[kwired]

OK...we're talking plumbing, not electrical, but I think terminology is the issue here. If you get a pressure "spike" for whatever reason, it can damage piping, instrumentation, or the poor customer's shower experience. None are good. Hydraulics 101. Smooth and slow. Oh..wait, that was the way I used to work! No wonder they were glad I retired!

Usually we are making analogies to plumbing to explain electricity, here we can make an one the other way - you need a surge arrestor to deal with the water hammer