Soft start shear pin trip

kwired

kwired

Electron manager
Location
NE Nebraska
Occupation
EC
Have a combustion blower fan on a boiler that we have had soft starter on for several years.

more recently have replaced with a different soft starter with more advanced features (AD SR35 series)

Had a little trouble early on with tweaking settings so it won't have random overload trip during starting. Been a while since it tripped but this last trip was a shear pin trip. I understand what that means. What I having trouble figuring out is the delay angle, not so much what it is but why it was different by quite a bit on this one starting event?

Attaching a snip from the log file, the trip event is about middle of the snip. Every other run event is pretty similar looking data, that trip event was very early in the start up and has much higher delay angle displayed. wondering if something going on on incoming supply maybe attributed to this? Was a one time thing and hasn't tripped since. Trip was nearly a week ago. This starts several times a day depending on steam usage.

Any ideas what happened on this run attempt?

Thanks in advance

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kwired said:
Have a combustion blower fan on a boiler that we have had soft starter on for several years.

more recently have replaced with a different soft starter with more advanced features (AD SR35 series)

Had a little trouble early on with tweaking settings so it won't have random overload trip during starting. Been a while since it tripped but this last trip was a shear pin trip. I understand what that means. What I having trouble figuring out is the delay angle, not so much what it is but why it was different by quite a bit on this one starting event?

Attaching a snip from the log file, the trip event is about middle of the snip. Every other run event is pretty similar looking data, that trip event was very early in the start up and has much higher delay angle displayed. wondering if something going on on incoming supply maybe attributed to this? Was a one time thing and hasn't tripped since. Trip was nearly a week ago. This starts several times a day depending on steam usage.

Any ideas what happened on this run attempt?

Thanks in advance

View attachment 2581957
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How do you get 15, 43, and 82 on a Dwell, when every other one is within 1 amp?
 
ptonsparky said:
Is the damper stuck open at these times?
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good question though I doubt it would be much of an issue here. 1.58 seconds of dwell time (time until full speed is reached) when the trip occurred.

I just now realized the (not sure why I missed it before) motor currents were 15, 43 and 82. Not sure why or if not a utility issue why it only happened this one time. I guess if it happened at 14:20 they would have been shut down for the day and everyone but office people are usually gone by then. Boiler runs 24/7 as needed to keep pressure and in winter there is fair amount of environmental heat run by steam.

Had it happened earlier certain production VFD's often will trip if under load when there is any kind of incoming power glitch, usually with under volt on DC bus as the fault code.

I also now see your next reply where you asked about that:oops:

Too much going on lately, been missing details I normally catch not just with work but seems to be with everything.
 
kwired said:
good question though I doubt it would be much of an issue here. 1.58 seconds of dwell time (time until full speed is reached) when the trip occurred.

I just now realized the (not sure why I missed it before) motor currents were 15, 43 and 82. Not sure why or if not a utility issue why it only happened this one time. I guess if it happened at 14:20 they would have been shut down for the day and everyone but office people are usually gone by then. Boiler runs 24/7 as needed to keep pressure and in winter there is fair amount of environmental heat run by steam.

Had it happened earlier certain production VFD's often will trip if under load when there is any kind of incoming power glitch, usually with under volt on DC bus as the fault code.

I also now see your next reply where you asked about that:oops:

Too much going on lately, been missing details I normally catch not just with work but seems to be with everything.
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Retire and you have the time to scrutinize other's problems.
I just wish I had the smarts to make sense of it.
Yea, now I wish I had paid more attention in school
 
ptonsparky said:
Well, that was interesting. CoPilot for the first time with a real search. It managed to sort through my questions and come back with relevant answers.

Other than a possibility of an SCR not firing correctly on occasion, the blower sticks periodically. Imagine that.
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Hope not. Even though this boiler was new back in about 1985 the entire blower assembly was replaced in the past 6 months. Can't believe how quiet it is now compared to what it has sounded like for many years. They been fighting bearing failures for a long time and trying to balance the blower wheel several times in past 15-20 years. In fact soft starter was first introduced because of frequent bearing failures. Kind of started out as, if they tightened belts enough so they didn't squeal during acceleration the bearings wouldn't last all that long. If they left belts a little loose, the bearings lasted longer but they had to replace belts pretty frequently. Soft starter did help those issues but bearings still were being replaced pretty frequently as time went on. Then there were several attempts at balancing the blower wheel. I think possibly a bent shaft was maybe the biggest offender. The pulley ratio is a speed increase from motor to the blower wheel. Not a major increase but yes still there is some significant momentum when it is running. 15 hp motor though normal running amps is more in the 10 hp range, probably designed that way for sake of the motor starts.
 
ptonsparky said:
15 HP combustion blower...jeesh. most I've seen is maybe 1.
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Not sure the capacity, probably kind of a small boiler for many industrial applications these days but still a lot more than a typical hydronic heat boiler as it is for process steam. Main vessel is maybe 10-12 feet diameter and 25-30 feet long. The heated air passes through tubes within the main vessel for transferring heat to the water in the vessel.

Possibly more boiler than current user needs but it came with the plant when Mid-America Dairy closed pretty much every plant they had in the state about 30 years ago. Current owner probably bought the plant for less than a similar replacement boiler would have cost to have installed. They did sell majority of the cheese making equipment to deter potential competition from taking over the facility
 
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