Motor Ground
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- čas přidán 26. 08. 2024
- In this video, I describe what ground is when we are talking about a motor. How a ground happens and how to find a ground.
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Thanks for replying to my question. I would have attach a ground under the fan shroud to connect to one of those bolts.
You can attach it to the underside of the motor as it is hanging. So that it is far away from the fan shroud. And away from the fan. I have had to do it like that several times. Good luck!
Best explanation. You have it in you sir keep up a good work.
Thank you so much and thank you for watching!!!
All those months of class and you made it easy in minutes.
Ha ha. Thank you!!!! After teaching all of these years I just put it out there the easiest way for you guys to understand. I’m glad I could help and keep watching my videos and learning! Thanks!
Thank you for making this video man. I have a pretty good understanding of circuits but sometimes over look simple things like ensuring everything on the case is connected to ground. Bought a bench grinder (Ac induction motor) a while ago and just recently started using it. Normally, I go into my shop with boots on but I needed something quickly so I just went in bare foot. I was sitting at my bench while on the phone and touched a part of the case that had a little bit of paint missing and got a nasty shock. I unplugged it and now today I'm taking it apart to find out why. Whoever made this connected the ground to the base of the grinder and made no connection to the case ng for the motor. So it's storing energy in a magnetic field and slowly discharging through a resistor but while inactive there's 5-20vac across the case. Like you stated earlier it CAN kill you but not always and man even that low of voltage still hurts. Like one of those prank taser lighters that were out in the late 90s early 2000s. Thankfully not a painful as 120vac and man does that hurt! Anyways, your video reminded me to test continuity and behold the case was isolated from the ground. So thanks man I appreciate this video!
Wow! That is quite the story! Thank you for sharing it with me! I remember having an issue similar to yours, but with a washing machine years ago! And yes! I remember those prank lighters and gum packets that they sold that will shock you when you grabbed it! Those were the days! Thanks for watching and I'm glad you like the video!
You make everything much easier compared to my HVAC TEACHER, I’m currently in HVAC school I have 8 more months to go!
He is such a great teacher
Thank you for your comment. I really appreciate it. I just started an online class April 12. 2021. I'm sorry I just saw your message.
Great video and explanation 👍
Thank you and thank you for watching!!!
Good explanation of motor ground. Thanks
Thank you so much! I appreciate your comments! Good luck out there and keep learning!
The person could be touching another grounded product with that other hand too. It does not have to go to ground through the feet. That current to ground will trip GFCI's, ground fault circuit interrupters, if used to power these devices. By the way, high tech motor controls or inverters create the main current by switching it on and off very fast. This high frequency current will travel from the motor windings to the chassis easier than the 60 hz. This too will trip a GFCI since most are only specified to trip at 60 hz, not at lower or higher frequencies found in higher tech control systems.
Yes, you are so correct! It does not have to go to ground through the feet but it could be through the other hand or an elbow or like it happened to me through the forehead. Yes, a GFCI was tripp but typically we do not use GFCI's on motors. For example in the state of Virginia GFCI's are only required in a room where there is water or within 6 feet of some thing that has water even if it is in another room. In class I go over how VFDs works and typically I will draw the schematic for a VFD so that student can see the components and how it works. I have never ran into a motor that is hooked up to a VFD and a GFCI. I guess maybe I will look into, when and where a GFCI is used in conjunction with a VFD and a motor? Thank you for your comments it gives me something to look into!
@@AirConAcademy Appliace manufacturers have been using VFD's for some years now. If an appliance is plugged into a GFCI it's likely to trip. Consumers were complaining about nuisance trips and I was asked to look into them. Spec's only state how they are to perform at 60 Hz, nothing defined for higher or lower frequencies. Since appliances appear next to each other the opposite hand is highly likely to touch a grounged product. Not only motors but also user interfaces. The power supplies in them are commonly switch mode, meaning line based high freq switching. User interfaces can be thin pieces of plastic, common dielectric materials, so now you could be the other plate of that cap to ground. Fun stuff.
@@chrisscriber9592 OHHHHH OK LOL I had no idea at first that you were talking about appliances. Yes, I knew that they had been using VFD's on appliances and such I don't know if I missed it but I didn't know before that you were talking about appliances. Now I see why you were talking about VFDs being hooked up to GFCI's. Now it all makes sense. I like to get into frequencies and magnetic fields and so on they are so many different things that could happen. I find it all so interesting! And I do like to read about it. Thank you for clarifying that for me.!
@@AirConAcademy VFD's used are created by the Appliance control manufacturers in the home appliances. Commercial units typically use industrial grade VFD's.
FYI: Power and signal harnesses are typically run throughout the machines in the same bundle. If you consider the copper in the wires a plate in a capacitor and the insulation as the dielectric you can predict high frequency coupling to more sensitive harnesses. You can minimize the impact by simply keeping the HF and sensitive harnesses even a 1/2 inch apart but this adds cost to the products. Cost is highly critical in these products.
Thanks for this video .looking forward to u making video on using a meggar
Kenneth Lobo coming soon!!
Very nice.... 😊 thanks
Thank you! And thank you for watching!
See you soon too bro.
Thank you! :-)
If there is a PE conductor attached to the motor,will you still recommend a case ground?
I'm sorry, I am not sure what you mean by PE? We need to make sure that if any of the electricity goes to the casing, it travels to a good ground. That is why you must always have a ground wire. Whatever the PE is, if it is allowing the electricity to go to ground it might be safe? But it's always best to have a separate ground wire! Remember with electrical safety we don't want to take chances. I hope this helps. Thank you for watching!
Thank you
Thank you!!!
Why is it when i connect the ground wire from my motor back to the vfd the breaker trips but without a ground the motor runs fine?
It sounds like you have some feedback or maybe you have a ground in the motor! A lot of times the motors are insulated at the mounting so the only way for the electrons to get to ground would be through the ground wire.
Without the ground wire connected, the casing would be energized, but the electrons could not get to ground, until you connect the ground wire. This is why when you connect a ground wire to the VFD ground it trips. Test the motor and see if it is grounded. I hope this helps! Thank you for watching and thank you for asking a question!
I purchase a new 1.5 hp 15 amp single phase ac motor that does not have a ground wire with the wiring bundle. How can I add a ground wire to the motor to prevent shock?
Take a look where the wires go into the motor, see if there is a green screw at that point and you can attach the ground wire to it. If not, what I have done is our house loosen one of the bolts that hold the motor together, in other words the bolts that go from one end of the motor to the other end of the motor, and then I attach my ground wire to that. The ground is supposed to provide a path for the electricity to go from the casing to ground if there's a problem. I hope this answers your question.!!!
I have a unit that sometimes the breaker Tripping, if I do reset the contact will start at normal operations, an then randomly it will do it again, we replace the breaker, cap is ok install a hard start kit and still doing, any recommendations?
Unfortunately from what you are telling me you have one of those floating grounds. You have a few things you could do. . One is to keep resetting the breaker and most likely whatever has the floating around will make a good ground and not be able to reset the breaker again. I believe it might be your compressor that has that. That is where I have seen this a lot of times. Your other option is to check it with a megger. Another option that I can think of is to disconnect the 24V wire from the compressor contactor coil, so you do not run the compressor and see if the breaker trips. I mean run the fans, like the condenser fan motor and the evaporator fan motor to see if that trips the breaker. This will tell you that it is the compressor. Another suggestion is that you would check the wiring. You may have a wire that is rubbing against the casing/chassis or something metal and the insulation has worn. Because of that sometimes it goes to ground and sometimes it does not. This would be on the high-voltage wires going to the compressor or the fans. I would check the wiring first like I said just now and then go on to other things. Good luck I hope you find it!
im fixing up an old table saw and it looks like the previous owner bypassed the ground somehow. it had the three prong plug but the ground was taped off and not connected to anything. can I reconnect the ground to anywhere on the motor housing?
Yes, you can connect the ground anywhere on the housing. That will make the motor safe in case you have a ground on that motor at some point.
A motor have ground terminals on the box and frame. Should they both ground?
The motor casing and the box that are on the frame should be grounded for safety reasons. That way if something goes wrong internally with the motor the current will go to ground and not through the technician or whom ever touches the motor.
i got a C frame motor do i just bolt a ground motor to the housing?
So if the electricity flows through the load and back to source we aren`t using electricity, just borrowing it, and it flows from us to our neighbours and to their neighbours. We are led to believe we have consumed that power. Seems an underhand trick, do you agree ?
Actually the reason for my post is to ask for help.
I have salvaged a 12v ambulance winch system which is wired through a box of tricks to have an E stop, forward/reverse, on/off etc.
I just want to power this motor by sending 12v to the brake and 12v to run the motor and have my own reverse switch when needed.
The motor has 3 wires feeding the brushes around the rotor. As far as I can find out the RED is Positive, the BLACK is Negative and the WHITE is Neutral.
Can I connect the neutral to the earth on the 12v psu I am using. Thanks for any help.
On the first part of your message. It is the electrons that are moving back-and-forth and they're going right to the transformer that is outside in the pole. It is not going to your neighbors or the other neighbor. It is making a big loop from the toilet in the transformer to your house, and then back to the same coil in that same transformer. So we're using basically the same electrons. On the second part, DC motors, meaning, the motors running off of batteries, are totally different than AC motors. Like the ones that run the fan in the heater or air conditioner for your house. One of the problems is that you need to know if your motor is wired in series or in parallel. Meaning is the electricity going through the brushes through the commutator, and then to the stater, or is electricity going to the brushes and to the stater and are these two wires together at the outlet and is that why you have three wires? Unfortunately, in the field, we don't use DC motors that much so I don't have a video on how DC motors are wired. I used to teach DC motors. That is why I mentioned those two different ways. If you have three wires, that is basically telling me, and I might be wrong, because I am not there to look at the motor, that you have one wire from the battery or switch going to the brushes, another wire going also from the same side of the battery possibly through a switch to the stater. As electricity travels through the brushes, and into the Commutator , and then through the stater, both of these are wired together to what you are calling that third wire common. That would go to the other side of the battery to complete the circuit. I hope this helps a little. If not send me another message, but hooking it up to ground is not going to do anything. Don't do that because the batteries are not grounded to earth. Only alternating current/AC is hooked up to ground. Thank you for watching and let me know if you have any questions.
@@AirConAcademy Thanks very much for your lengthy reply, it is much appreciated.
I am not sure how to go about testing for series or parallel. All 3 connections are connected via the brushes to the commutator. I get a continuity beep probing any combo of the brushes. Does that help.
Sorry for my super basic approach.
@@codepuncher yes you would get continuity across all three. If you could email me and send me some pictures. Maybe a little better explanation. jh@airconacademy.com
@@AirConAcademy some images sent. regards
@@codepuncher i hope you got my email
I am using a brushless motor in a diy project. It comes with a ground wire but I don't know what to do with it. My project only needs the POS and negative (battery charging). Can someone please tell me what to do with it? Ground bus? Very new.
The ground wire is just for safety. You can take that ground wire and connect it to the chassis, or you can connected to an actual ground. But if you're talking about positive and negative you must be talking about a battery so you can connect it to the chassis or in other words the framework that the motor is connected to
@@AirConAcademy Thank you so much ☺️
@@AirConAcademy If I may, I have one more question to ask. Can I safely run a DC electric motor at 175 rpms over rated? Is that a biggy?
@@sharilyn8262 If you are talking about running the motor 175 RPM higher then rated speed, you need to be careful. Centrifugal force can take a motor apart if the speed is exceeded it can fly apart!!!! It may be safe but!!! be very careful over speeding a motor.
@@AirConAcademy Woah 😳 thank you!
Difference between short, ground and overcurrent?
Hello Julio thank for the tips, but why you don’t make a Spanish channel? Could be good. Thank again.
I had thought about that and because of your suggestion I might think think about it even more. Thank you for the suggestion.
@@AirConAcademy thank you for sharing your knowledge with us . I appreciate it .
@@ac4usa887 I remember how hard it was when I was starting out. And people did not want to teach you anything. I’m just trying to help you guys out there! But thank you for watching! And your suggestions!
Well insulated with extra electrical tape
Good! Just make sure that the fan is not going to hit it!
That motor looks isolated.
Abel Urrutia yes. That is why it is dangerous, you become the ground And. Zzzap!!! You got shocked.