VFD's blowing fuses

Little Jonny · February 16th, 2009, 04:42 PM

Guys, my brand new VFD driven fans are blowing 50amp fuses over night, almost daily. All the geniuses have looked at it and cant seem to find any problems. Any clues???

iOperate · February 16th, 2009, 05:01 PM

What are these fan supplying? Is there more demand at night vs. day time? Do these fans ever shut down on a typical day?

TheSuper · February 16th, 2009, 07:19 PM

Do you know the damper/inlet vane position when the fuse blows?

Little Jonny · February 16th, 2009, 10:37 PM

Quote:

Originally Posted by iOperate

What are these fan supplying? Is there more demand at night vs. day time? Do these fans ever shut down on a typical day?

They are fresh air fans. Less demand at night, almost minimal. May be 30%. Yes, they shut down at midnight and start up at 4am.

Electro · February 17th, 2009, 01:03 AM

Maybe the drives are not properly matched to the motors ?

143 · February 17th, 2009, 02:53 PM

How many fuses is it blowing?

Little Jonny · February 17th, 2009, 07:36 PM

Quote:

Originally Posted by 143

How many fuses is it blowing?

Just one phase but its never the same.

Lazy Pup · February 17th, 2009, 10:24 PM

Jonny, you need to hook up an analyser to understand the conditions its tripping under. Such as time, voltage, amps drawn etc. Does your automation system track any of this? You say its a VFD so it must be microprocessor controlled. Do you have any fault codes? Come on, cough up some codes and lets see where we can take this.

sparky · February 17th, 2009, 10:27 PM

Quote:

Originally Posted by Lazy Pup

Jonny, you need to hook up an analyser to understand the conditions its tripping under. Such as time, voltage, amps drawn etc. Does your automation system track any of this? You say its a VFD so it must be microprocessor controlled. Do you have any fault codes? Come on, cough up some codes and lets see where we can take this.

I think Lazy Pup is on to something here............................

ryanedwards · March 3rd, 2009, 06:19 PM

Sounds like you have a voltage problem in the building. This fuse problem is common when your incoming power is not clean and it will drive your mechanics nuts because it is intermittent. You may have voltage spikes or dips that will blow your fuses or trip off your unit, or maybe you have harmonics on the line that your drives don't like. Hook a scope up to your incoming power and be patient. You will have to set it up to sample at intervals as fine as possible as the fluctuations by be short (half second). This means, you may be resetting it often. You may have to do this for quite a while before you can prove that you have an incoming power problem from the grid. I have been through this before, and it can be a very painful process.

143 · March 4th, 2009, 12:35 AM

Guys, is it just one fan that is blowing fuses or is it a few of them?

Little Jonny · March 5th, 2009, 08:33 PM

Quote:

Originally Posted by 143

Guys, is it just one fan that is blowing fuses or is it a few of them?

Two identical fans but they are not consistent meaning, very rarely will both fans blow fuses on the same day. They kinda take turns.

iOperate · March 6th, 2009, 06:11 AM

Quote:

Originally Posted by ryanedwards

Sounds like you have a voltage problem in the building. This fuse problem is common when your incoming power is not clean and it will drive your mechanics nuts because it is intermittent. You may have voltage spikes or dips that will blow your fuses or trip off your unit, or maybe you have harmonics on the line that your drives don't like. Hook a scope up to your incoming power and be patient. You will have to set it up to sample at intervals as fine as possible as the fluctuations by be short (half second). This means, you may be resetting it often. You may have to do this for quite a while before you can prove that you have an incoming power problem from the grid. I have been through this before, and it can be a very painful process.

I think Ryan is on to something here. If they are tripping during a specific time window (eg: 4am to 6am) then you can safely make an assumption provided they are not tripping on start up. I had a similar problem a while back and it was determined to be a power quality (low voltage) issue.

ryanedwards · March 17th, 2009, 11:30 AM

Wanted to follow up to see what finally came out of this? Let us know!

February 16th, 2009, 04:42 PM	#1
Little Jonny Senior Member Join Date: Jan 2009 Location: Toronto, Canada. Gender: Male Posts: 137	VFD's blowing fuses Guys, my brand new VFD driven fans are blowing 50amp fuses over night, almost daily. All the geniuses have looked at it and cant seem to find any problems. Any clues???

February 16th, 2009, 05:01 PM	#2
iOperate Super Moderator Join Date: Jan 2009 Location: 3rd Rock From The Sun Gender: Male Posts: 101	What are these fan supplying? Is there more demand at night vs. day time? Do these fans ever shut down on a typical day?

February 16th, 2009, 07:19 PM	#3
TheSuper Administrator Join Date: Jan 2009 Location: Plano, Texas, Posts: 94	Do you know the damper/inlet vane position when the fuse blows?

February 17th, 2009, 01:03 AM	#5
Electro Junior Member Join Date: Jan 2009 Location: Peterborough Posts: 5	Maybe the drives are not properly matched to the motors ?

February 17th, 2009, 02:53 PM	#6
143 Member Join Date: Jan 2009 Posts: 43	How many fuses is it blowing?

February 17th, 2009, 10:24 PM	#8
Lazy Pup Junior Member Join Date: Feb 2009 Location: Calgary, AB. Gender: Dude Posts: 21	Jonny, you need to hook up an analyser to understand the conditions its tripping under. Such as time, voltage, amps drawn etc. Does your automation system track any of this? You say its a VFD so it must be microprocessor controlled. Do you have any fault codes? Come on, cough up some codes and lets see where we can take this.

March 3rd, 2009, 06:19 PM	#10
ryanedwards Junior Member Join Date: Jan 2009 Location: Claremont, Ontario Gender: Male Posts: 18	Sounds like you have a voltage problem in the building. This fuse problem is common when your incoming power is not clean and it will drive your mechanics nuts because it is intermittent. You may have voltage spikes or dips that will blow your fuses or trip off your unit, or maybe you have harmonics on the line that your drives don't like. Hook a scope up to your incoming power and be patient. You will have to set it up to sample at intervals as fine as possible as the fluctuations by be short (half second). This means, you may be resetting it often. You may have to do this for quite a while before you can prove that you have an incoming power problem from the grid. I have been through this before, and it can be a very painful process.

March 4th, 2009, 12:35 AM	#11
143 Member Join Date: Jan 2009 Posts: 43	Guys, is it just one fan that is blowing fuses or is it a few of them?

March 17th, 2009, 11:30 AM	#14
ryanedwards Junior Member Join Date: Jan 2009 Location: Claremont, Ontario Gender: Male Posts: 18	Wanted to follow up to see what finally came out of this? Let us know!

VFD's blowing fuses

Electrical, Mechanical and Control Systems