The computer and other such modern devices that are digital in nature (in abroad sense) like DVDs and other light weight electronics(all terms relative) use SMPS power supplies. In an SMPS, input mains is first rectified and then this dc is used in the smps circuitry. The amp power supply is made from a step down transformer. Could be a toroid, EI or other type. This is the transformer I am referring to. If u connect the square wave ups to this transformer, the primary coil will overheat, and damage the insulation.
Gajanan Phadte
Gajanan Phadte
gmphadte said:
My inverter says its modified sine wave, so does that change something or not, and its only 400watt inverter so I dont think it have enough power to heat up anything
If u have a spare, small transformer lying around, just connect it to the ups without any load on the secondary. If it heats up, then do not connect your amp.
If the ups has enough power and the test transformer does not heat up, try inserting a 10ohms high wattage resistor in series. Total load should be less than 400watts.
Gajanan Phadte
If the ups has enough power and the test transformer does not heat up, try inserting a 10ohms high wattage resistor in series. Total load should be less than 400watts.
Gajanan Phadte
Are we getting off topic or not, will your method solve my problem with my inverter getting tripped by something, I don’t care if the transformer overheats tho?
jacquesl said:
I think he is addressing the possible problem of overheating your power transformer.
Perhaps you missed what I was saying in this post above.
If you follow the link in the post, you will see that there is a company which addresses the problem of UPS tripping by adding a series inductor (or inductors - one in each leg) in the mains line between your UPS and your load. (Amp)
Perhaps if you re-read that post you will find some help there.
Smoothing the square wave to more closely resemble a sine wave will help reduce the noise from the UPS, reduce any overheating, and perhaps eliminate the tripping problem.
I'm sorry, but as a new member it takes a looong time before my posts show up and it's possible you missed it for that reason. I don't know how long this goes on, but it makes it rather difficult to help.
I’ve seen your post but for some reason, I dint think that your idea would work and your links, it’s interesting, but its commercial products and I don’t think it would be needed for a simple solution to solve my problem and that might be expensive to buy such a device, I might just buy a bigger inverter that would cost less, but I think the problem is with my amp.
My transformer is a big one, but with a interval of a couple of milliseconds I don’t think the inrush current will be that big deal, I am good in electronics but not a professor.
My UPS did work like in that mater with my amp in UPS line but after I replaced my inverter with a new type of inverter that has new smart functions and less parts, now its trips as soon as the mains drop and the power goes over from AC to Battery, but If I unplug the amp from the UPS line, then my UPS function normal without tripping, and I really like my homemade amp because it can play hard without breaking because of the oversized heatsinks and 2 backup fans that switches on then the amp heats up to much
My question is basically, would a Suppression Cap do the job or a normal high voltage ceramic cap not electrolyte cap though ?
Why does all amps have a cap in parallel with their mains line “230v” that goes into the step transformer ?
My transformer is a big one, but with a interval of a couple of milliseconds I don’t think the inrush current will be that big deal, I am good in electronics but not a professor.
My UPS did work like in that mater with my amp in UPS line but after I replaced my inverter with a new type of inverter that has new smart functions and less parts, now its trips as soon as the mains drop and the power goes over from AC to Battery, but If I unplug the amp from the UPS line, then my UPS function normal without tripping, and I really like my homemade amp because it can play hard without breaking because of the oversized heatsinks and 2 backup fans that switches on then the amp heats up to much
My question is basically, would a Suppression Cap do the job or a normal high voltage ceramic cap not electrolyte cap though ?
Why does all amps have a cap in parallel with their mains line “230v” that goes into the step transformer ?
jacquesl said:
"modified sine wave" is basically marketing speak to say that it is not a pure sine wave. Sounds much better than saying "this UPS/Inverter puts out jagged AC that is not suited to all electronic devices." 😉
What size is the toroid in the amplifier?
What is the primary resistance of the amp toroid?
What soft start have you fitted?
What is the short term current limit of the inverter?
What is the primary resistance of the amp toroid?
What soft start have you fitted?
What is the short term current limit of the inverter?
An externally hosted image should be here but it was not working when we last tested it.
This is an exported image from TinyCAD, so I could draw stuff.
does that transformer model apply to the start up case (no core flux) as well as when the transformer core has established it's operating flux?
I hadn't thought about that case actually.
It's a model I dug up a while ago looking to generate a good spice model.
I found it at Butler Winding, here
Intuitively, I would expect the initial current to be higher.
I found a book on Google books which states:
Since the relation between the current i and the magnetic flux density B is empirically given by the magnetic cycle of the material and cannot be expressed with sufficient accuracy by a mathematical equation the problem of determining the transient starting current of a transformer is investigated by constructing the curves of current and magnetic flux density
Theory and Calculation of Transient Electric Phenomena and Oscillations; By Charles Proteus Steinmetz
(65.00 on Amazon, maybe after I buy everything else on my shopping list 😉 )
I took a look at the curves and indeed the startup current is higher, but not orders of magnitude. Well, 1 order of magnitude, actually.
The table on P188 Shows ~510 A for the case of 50A load. There is a neat curve of actual startup current on P. 190, fig. 47 showing startup current for the 25 Hz case. Bear in mind this is all for Iron, not powder cores. The curves they show are NOT for toroidal cores either. (pub in 1920)
Air losses should be lower.
I am DEFINITLY not an "expert" on transformers!
Roy.
It's a model I dug up a while ago looking to generate a good spice model.
I found it at Butler Winding, here
Intuitively, I would expect the initial current to be higher.
I found a book on Google books which states:
Since the relation between the current i and the magnetic flux density B is empirically given by the magnetic cycle of the material and cannot be expressed with sufficient accuracy by a mathematical equation the problem of determining the transient starting current of a transformer is investigated by constructing the curves of current and magnetic flux density
Theory and Calculation of Transient Electric Phenomena and Oscillations; By Charles Proteus Steinmetz
(65.00 on Amazon, maybe after I buy everything else on my shopping list 😉 )
I took a look at the curves and indeed the startup current is higher, but not orders of magnitude. Well, 1 order of magnitude, actually.
The table on P188 Shows ~510 A for the case of 50A load. There is a neat curve of actual startup current on P. 190, fig. 47 showing startup current for the 25 Hz case. Bear in mind this is all for Iron, not powder cores. The curves they show are NOT for toroidal cores either. (pub in 1920)
Air losses should be lower.
I am DEFINITLY not an "expert" on transformers!
Roy.
AndrewT said:
I don't know what’s the VA anymore because its a old project and the documentation is no longer with me.
Primary resistance is 3.7 Ohms
No soft start
400W continuous 800W peak
220Vac has a peak of ~310Vpk.
that voltage at peak waveform will try to shove 84Apk into the transformer, if you switch on near the peak.
If you switch on either side of peak then the worst current will be slightly less. This overload reduces rapidly and is substantially over in one or two cycles of the mains supply.
Then the current required to charge up the smoothing caps starts and continues a new overload condition that can last for one to three seconds, but much more if the cap bank is enormous.
Fit a soft start.
A two stage soft start might better suit the UPS.
a high resistor of say 50r + a power thermistor of 15r to 20r in series. Then bypass the whole resistance after about 300mS.
To reduce the severity of the charging overload think about adding a power thermistor 5r to 10r in the secondary and again bypass, but this time after 3seconds to 5Seconds. Try it with just the primary soft start and see how the UPS behaves.
I wonder if a DC blocker on the primary would offer any advantage? either to reduce the UPS load or reduce the running temp of the amp transformer.
that voltage at peak waveform will try to shove 84Apk into the transformer, if you switch on near the peak.
If you switch on either side of peak then the worst current will be slightly less. This overload reduces rapidly and is substantially over in one or two cycles of the mains supply.
Then the current required to charge up the smoothing caps starts and continues a new overload condition that can last for one to three seconds, but much more if the cap bank is enormous.
Fit a soft start.
A two stage soft start might better suit the UPS.
a high resistor of say 50r + a power thermistor of 15r to 20r in series. Then bypass the whole resistance after about 300mS.
To reduce the severity of the charging overload think about adding a power thermistor 5r to 10r in the secondary and again bypass, but this time after 3seconds to 5Seconds. Try it with just the primary soft start and see how the UPS behaves.
I wonder if a DC blocker on the primary would offer any advantage? either to reduce the UPS load or reduce the running temp of the amp transformer.
The amp transformer performs better at 60Hz. It's quite a feat to design a 50Hz transformer and I bet we could all benefit from a change to a higher frequency if we could start over again.
In South Africa all devices is fixed on 50Hz and 220 ~ 250 Volt my inverter can only do from 43 ~ 52 Hz
You see the power dip is only 2~3/25 of a second that extremely fast, do a soft start be needed ? i don't think so man? for a fast dip like this, I’ve tested the dip with a video camera recording a 60watt light bulb, and only 2 ~ 3 frames was down, and was from high to dimmed and 2 frames of and dimmed to high of the rest of the frames, very fast.
yes thats way it happens the most of the times
I personal think this is the problem why my inverter trips, will a cap in parallel solve the problem like in Post #29 like I mentioned that is fitted in all amps then you buy one at a store
You see the power dip is only 2~3/25 of a second that extremely fast, do a soft start be needed ? i don't think so man? for a fast dip like this, I’ve tested the dip with a video camera recording a 60watt light bulb, and only 2 ~ 3 frames was down, and was from high to dimmed and 2 frames of and dimmed to high of the rest of the frames, very fast.
yes thats way it happens the most of the times
I personal think this is the problem why my inverter trips, will a cap in parallel solve the problem like in Post #29 like I mentioned that is fitted in all amps then you buy one at a store
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