For such cases, breakers with a different drive curve are used, not B or C as usual.
One place to start study: https://www.farnell.com/datasheets/2307190.pdf
Ya but it was more a matter of the wire becoming a resistor, dropping the voltage, then the motor wants more current to compensate which compounds the issue. The saw would slow down onto the start windings. The guy was used to pushing the wood through the saw, but in this case, there wasn't the power to maintain the cut, the saw would stop, and blow the fuse.
Eventually, the guy realized to let the saw do the cutting 🙂
Eventually, the guy realized to let the saw do the cutting 🙂
Yes, this is true for industrial for industrial controls.
But for residential panels, I don't think you have a choice of breaker curves. Correct me if I'm wrong, but I've never seen any.
And that guy had a fused panel anyway. And yes, fuses are available with different response times, but for residential use, maybe not.
Then again, the last fuse panel I saw in a house was 30 years ago.
For Canadian requirements, a type “P” fuse is used for non-motor loads and type “D” fuses are used for electric heating and cycling loads circuits. Both fuses have low melting-point temperature elements. Low-Temp time delay plug fuses have thermal sensitivity are also for cycling loads and motor circuits. Type “S” plug fuses are time delay and tamper-resistant.
In my panel, I use P type...
In my panel, I use P type...
You have different breakers in Romania (Europe) than we have in Canada and the USA. (Frankly, I like yours better.)
For #14 nominal 15 Amp circuits like kodabmx remembers, there may have been a slower-blow fuse (I still have screw-fuses in the garage) but really only "Standard" time circuit breakers. (OK, there are the old Federal Pacific breakers which often don't trip even when smoking; they were lots of fun in the school where I worked.)
We don't want a looooong breaker on small circuits because we "coordinate" the hierarchy from small to main to transformer so that a contractor saw can't darken the whole neighborhood.
And of course if the saw motor is stalling, a bigger fuse isn't a real help. Just more heat in the wire.
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Ya the system in that house was a real mess. 6 fuses, a subpanel for the stove that had the furnace piggybacked off of one leg, a subpanel for the dryer, a subpanel for the water heater...
Then it was "upgraded" to FPE Stablok... They DO trip if you short or overload terribly, but a 15A breaker will hold 18A for days.
Then it was "upgraded" to FPE Stablok... They DO trip if you short or overload terribly, but a 15A breaker will hold 18A for days.
The breakers are supposed to be calibrated to protect the specified wire used in the installation. One circuit in my house (20 amp circuit) is subject to frequent 30 amp loads. It has never tripped the whole time I've lived here.
Where I live THHN wire is specified, which can handle a considerable overload. It can certainly handle larger current surges. I have a large air compressor in my garage. My garage is served by 2-15A dedicated circuits from the house. It's fed through underground wire, 14 gauge. The compressor draws up to a 150A surge when starting up. The breaker trips sometimes if it's really cold in the garage, but usually not. That's exactly how it's supposed to work.
IF the Euro-breaker specs applied to your circuits: 18A on 15A is a 1.2X overload and it actually is allowed to carry that for 2 hours; and is on the near-vertical part of the curve so "days" may be quite kosher.
At my school we often found that FPE breakers had been carrying a 2X overload for 20-30 minutes. The Euro-curve allows 1 or 2 minutes.
Eddie's motor, like many high-eff motors, can suck 10X running current at stand-still. This is allowed for about 1 Second. Assuming the rotor is not jammed (or oil-congealed) the rotor speed will come up a lot in a few cycles, make back-EMF, current falls quickly.
12X to 19X overcurrent brings in the "dead short" coil and trips-out quickly, with a few milliSeconds being about a limit for mechanical contraptions.
We rarely find circuits with less than 1% sag, so rarely >100X overcurrent. Breakers in 100A panels used to be rated for 10,000A fault current (raised to 22KA). My 100A feeder CAN'T suck over 800A, it sags bad. (I know the cause, the cure, the cost, and it is not a problem, even on laundry day.)
As said:
The breakers are supposed to be calibrated to protect the specified wire used in the installation.
The breakers are supposed to be calibrated to protect the specified wire used in the installation.
Then there was the electrical fire at 650 Parliament street... Breakers can't protect against this type of thing, but they don't put the vault in the building anymore, either.
There was some flooding of the vault that resulted in what I assume was a primary to secondary arc, sending 27.6kV where 208V should be.
“Once the system went into overload failure, the circuits routed above to the overhead floors caused the plastic sheathing of the wires to melt,” the report said. “These exposed wires impacted upon the plywood wall sheeting of the electrical cabinets and other nearby combustibles causing them to off gas and ignite.”
“The switchgear for the main service feed from the transformers was severely damaged, with evidence of arcing, and one of the service legs after the main fuses was damaged and consumed.”
https://www.thestar.com/news/gta/20...liament-fire-caused-65-million-in-damage.html
There was some flooding of the vault that resulted in what I assume was a primary to secondary arc, sending 27.6kV where 208V should be.
“Once the system went into overload failure, the circuits routed above to the overhead floors caused the plastic sheathing of the wires to melt,” the report said. “These exposed wires impacted upon the plywood wall sheeting of the electrical cabinets and other nearby combustibles causing them to off gas and ignite.”
“The switchgear for the main service feed from the transformers was severely damaged, with evidence of arcing, and one of the service legs after the main fuses was damaged and consumed.”
https://www.thestar.com/news/gta/20...liament-fire-caused-65-million-in-damage.html
I "repaired" an ebay battery I bought for my Fluke 123 Scopemeter. As noted by others on line, these come with both the connector pinout wrong and a wrong value of battery chemistry type identifying resistor. Too much hassle to return; easier to just do the work to make it right.
Overnight, it charged up to full capacity, if the indicator means anything. Back in business of having a portable 20 MHz scope, circa 1997.
Overnight, it charged up to full capacity, if the indicator means anything. Back in business of having a portable 20 MHz scope, circa 1997.
So today I decided I wanted more gain from the phono stage for sampling... So I dropped 6N2P into the 6N1P circuit complete with 240R cathode resistor.
The sim I get reflects performance... It's actually good, and no grid current (or the record would sound bitched LOL) 🙂
It's not quite accurate though - the load isn't a 66k resistor, but another 6N2P as a CCS.
The sim I get reflects performance... It's actually good, and no grid current (or the record would sound bitched LOL) 🙂
It's not quite accurate though - the load isn't a 66k resistor, but another 6N2P as a CCS.
Attachments
Ok. After consideration, it was actually adding more noise than gain compared the the 6N1. I will change the 240R to 1k and see if it's just grid current noise or something...
Hook timing on my daughter's Singer Model 626 sewing machine. About a 50 or 60 year old machine.
1991 era Technics SL-P170 CD player.
I did a repair on it back in 2020 - a 1uf cap on the servo board under the laser mech read 0.1uf, and caused it not to read disks.
Lately, on occasion, it ticked me off that it would skip at a certain part of the CD, any CD.
SO....... on the bench it went....again.
After some examination, that cap that I replaced was the culprit - it wasn't defective, it was a tad taller than the original, and the bottom of the laser mech rubbed the top of it just a hair... enough to cause the skipping.
Now a fresh cap, layed horizontally and the player is perfect again.
Oh, and by the way, the 3 mech suspension springs MUST be installed in the original places and not mixed up - or else the mech will shimmy and shake during use.
Also, I only have similar service manuals, not one for the SL-P170, so if anyone has that manual, I'd be glad to get a copy, I hate using "similar" manuals.
I did a repair on it back in 2020 - a 1uf cap on the servo board under the laser mech read 0.1uf, and caused it not to read disks.
Lately, on occasion, it ticked me off that it would skip at a certain part of the CD, any CD.
SO....... on the bench it went....again.
After some examination, that cap that I replaced was the culprit - it wasn't defective, it was a tad taller than the original, and the bottom of the laser mech rubbed the top of it just a hair... enough to cause the skipping.
Now a fresh cap, layed horizontally and the player is perfect again.
Oh, and by the way, the 3 mech suspension springs MUST be installed in the original places and not mixed up - or else the mech will shimmy and shake during use.
Also, I only have similar service manuals, not one for the SL-P170, so if anyone has that manual, I'd be glad to get a copy, I hate using "similar" manuals.
Tonight on the bench - a Zenith DTT900 digital TV converter box.
Unit kept shutting down.
Changed out 4 caps (circled) on the SMPS supply board.
Works fine now.
Yes, we still have some CRT tv's around the house.
Unit kept shutting down.
Changed out 4 caps (circled) on the SMPS supply board.
Works fine now.
Yes, we still have some CRT tv's around the house.
And this type of equipment tends to run continuously or near continuously at its design maximum, not spending most of its life at far less than the maximum it could produce.
Yes.
The Zenith converter ouputs 5V and 3.4V + 2.3V continuously.
At the AC plug it draws 0.6W in standby, 6W when on.
Odd that those "energy conservation worriers" want to spout about saving energy, promote windmills, etc..
Yet we've got these devices trickling power all over the globe.
Blame it on "remote control" convenience.
And not 3 watts when turned down to low listening levels - 6 watts all the time. How long would your stereo receiver last if it were turned up to distortion all the time? Not very - it would need recapping long before the typical 20 years. Probably blow one or two sets of output transistors, too.
My Dish DVR draw the same amount of power “on” or “off”. Will go to sleep mode if “it appears no one is watching TV”. Why? No idea - it still puts out a still image (telling you how to turn it on). And all the background tasks continue to run. Can you say waste of electricity? I thought you could.
My Dish DVR draw the same amount of power “on” or “off”. Will go to sleep mode if “it appears no one is watching TV”. Why? No idea - it still puts out a still image (telling you how to turn it on). And all the background tasks continue to run. Can you say waste of electricity? I thought you could.