I can't stress it enough, don't just change fuses, look everything over before replacing a bad fuse, fuses don't just go bad, something caused them to go bad!
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3 phase Gaspacks that use 2 pole contactors connect one leg direct and it feeds back through the compressor windings.
Thank Jesus the sporlan is back 😰
Sometimes, fuses just go bad.
But here I suspect the combination of low voltage and bad contactor – if just for a moment the contactor did not make proper contact, that would burn the fuse. Service area Ottawa??
The voltage floor is just to be sure the machine doesn't crest over the total amps value with everything drawing at max allowance.
Does make sense since amps go up as voltage drops…. and it snowballs at a certain point to failure.
I guess one thing I would do is verify voltage source at the main panel feed that leads out to the roof to see if the line leading up is causing excessive resistance.
When the voltage goes low, the amperage goes high. Maybe the low voltage went really low at some point and the amps went to high and blew the fues. Also maybe the compressor or fan motor would not start with low voltage and blew the fuse. The low voltage makes the motors and compressor run very hot. Could also be a voltage spike or dip from the electric company or a lightening hit.
An autopsy of the fuse could give clues as to the nature what caused the failure. I’m wondering if it was heat from a weak connection on the fuse clip. Also looking at the diagram to find what components are connected to that fuse would narrow the search field.
Could be the one that blew wasn't a TD style? L1 fuse FLNR is definitely TD type but couldn't tell on L2 L3 in video
Power surges are common in the older buildings I work on. Every time we get a report there's a power surge one or two units don't come back on. Occasionally we find bad fuses afterwards but we check for shorts. I had no clue that low of a voltage could be that great of an issue. I'll have to recommend some of the older building PMs have an electrician look at the mains.
The Mimi,u, Voltage Ratings are to protect the motors…
Motors will always use the same amount of Watts when they run and since [Watts = Amps x Volts], when the available line Voltage drops, the Amperage draw rises to compensate and if a motor draws too many Amps for too long, Bad Things Happen and you need a new motor…
fuses do degrade and fail overtime, each time a motor starts and strains that fuse it will degrade its life over time so blown fuses are expected, hence whyn they should be replaced every 10 years
I always wondered, does rust-inhibiting paint on the freon lines help prevent leaks?
I just had this exact issue after a storm and power outage. Checked everything to ground and swapped the fuse. Assume some voltage drops from the utility during or after storm outage may have caused it. Love your videos Chris.
At what point is the voltage low enough that you would consider either bringing in an electrician to check things out, or even contact the electricity supplier to see if they need to make adjustments to transformers?
Doesn't look like the first time with all those dead fuses in the disconnect.
I am too old to become a tech. I have some electrical experience. I don't want to repair my own equipment but I watch you week after week. I wish more people had the humanity you express in the last statement of your videos. There is too much hate in our world these days. Service area Orleans??
One thing I always check on a 3 phase system fuse blow is whether the fuse that blows is on the line powering the transformer. If you test the main components and everything is ok there might be something to check on the transformer or on the control side, although a 30 amp fuse should take out the lower voltage wires and be easier to see but you never know. Great video and always enjoyable to watch you and knowing that you are training others as you go.
Ive had one of my car fuse blow just because and after replacing it everything worked ok
Fuses don't go bad on their own, but they can become marginal after repeated (near) overload. Combine that with a hot day, high load, low voltage, dirty contractor, bad capacitor, abused compressor, etc etc and you can have a fuse intermittently pop. Sometimes it isn't just one thing, but instead a lot of little things that add up. Just like how the main breaker in your horror story should not have failed to reset from an overload condition, but after years of heavy use, it finally gave up the ghost. The same can happen to fuses. Sometimes just replacing the fuse will have you back there in a day or a week, other times it might hold up for a year or more.
It’s not smart to push the contactor in with a screw driver
Just a quick question, at the local subway where I work, the aircon isn't blowing cold air out, so its like 30°c in the whole building. The thermostat is set at 15°c constantly, but the aircon just isn't cooling. It's still running because I can hear it (it's in the building) so it hasn't shut off because of something internal. It's a temperzone unit. I think the thermostat is dead. Any advice? Are you in Barrhaven ?
Well said, fuses don't go bad on their own.
Sure, fuse holders can corrode and heat up and this can blow fuses or decrease their effective current rating. But this is not caused by the fuse itself.
Are the fuses for this type of unit directional? I noticed at the start of the diag the third fuse was a different direction than the others.
:] i had a fuse break because of age made it for over 60 years Are you in Orleans ?
TIME DELAY ON BREAK,thanks for sharing.
i had a similar problem were the main power to the building had bad connections in the fuse box causing the voltage to drop over time and trip the overload protection on the compressor! couldve been a similar case here considering the drop in voltage you saw.
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I see spiders there. A spider could be the cause.. now toasted and no longer a short.
Low voltage means more resistance and heat which can kill a fuse
meant to say short cycling and thus compressor is starting without pressures equalising
How much did you charge the customer and for each individual item?
Chris… Fantastic video… my only thoughts are a weak fuse or starting under load…. I.E short cycling Are you in Nepean ?
I finish HVAC school with my certification and EPA in about a month and I really hope I get an instructor as good as you , it it normal to feel intimidated and overwhelmed despite being in school the last 9 months ? Are you in Kanata ?
Well, a fuse isn't a "black box". If there's no connection through it and someone thinks it "went bad", not got blown by the overcurrent – they can take two pliers and crack it open. And there's going to be a visible difference between a melted conductor inside it and, say, a corroded (that's pretty much the only way it can actually "go bad") conductor. I've seen fuses eaten by corrosion (not in a normal HVAC, but in an industrial situation with corrosive substances involved) a few times, but it happens to them way less often than to breaker switches, for example. And if you don't see wires eaten by the corrosion next to the fuse, there's pretty much no chance the fuse itself is corroded unless it's been taken from a box that's been sitting under a leaking battery or something.
Love your videos. Learning something new every time
ok the universe is right again, this video is sponsored by sporlan.
What a mess. The wiring on all this equipment is horrible. Looks like the bare minimum is used everywhere. Not even a thermal overload relay on the compressors, come on. This would never be allowed here in Europe. Bad contact in one of the phases in the contactor is probably what took the fuse out. You're lucky the compressor survived without any thermal overload protection. That said, I really really enjoy your videos! Thank you for doing the extra effort to take us along the way!
"fuses don't blow without reason" They do! They are thin wires, that should burn when overcurrent but at the same time because they are so thin, they are a kind of resistors… so they get warm during normal operation. So warm-cold-warm-cold… you know 😉 And then when you have higher inrush currents, there is a possibility, that this can blow a already loaded fuse, especially when they run near their rated current.
Sure, you always HAVE to check. Not just replace the fuse. absolutely right. But they can go bad. 🙂
greeting from an electrician 🙂
Voltage sag on one leg causing an over current on that leg.
I hear a bearing failure on that roof..? Sounds like metal on metal.
You should be kind to everyone unless they are a Tory!
Power grid in California is probably the cause. Too much load to keep stable power. Would be interesting to put a recording meter or oscope on the legs and see how high and low it will go. Sadly the lack of upgrading grid and power generation is putting things below performance of many 3rd world systems 🙁 So much growth in demand along with a decline in system capacity
Could a brown out cause the fuse to blow? Lower voltage =higher amps?
2035: What's that in the backyard covered in weeds? Oh, that's my old Tesla. It's been there more than 10 years. And sitting next to it is the economizer parts for my buildings AC.
Add carbon tracing on all insulated materials in components to your visual inspections. A pen light helps kinda light up any paths for voltage to travel terminal to terminal Just another suggestion
As voltage drops amperage goes up, knowing you’re in California and it’s already running at the minimum voltage, you may have had a brown out in one phase right at start up of the compressor and blew the fuse
Why the voltage was so low? you think that will cause future problem? Service area Barrhaven??
The low voltage of 197 might be because of the amount of reluctance in either the compressor or the fan motors. The reluctance does affect operation of some components.
904 thumbs up
exahust fan in the background sounds like shit!
Most probable overvolt peak in that line. Service area Kanata??
What if the voltage dropped down to 150 during the heat of the day brown out. Could have that caused the fuse to go bad?
fuses and breakers do wear out, and if an electrician says they don't i tell my customers to get another electrician. they are use to Resistance loads. inductive(any type of coil like motors) draw very high amps when starting. that's why we use time delay fuses.