As long one use only android smartphone this is absolute correct.
Regardless - not everyone knows the solution from EMEKO.
For me to open links isn't a pain in the rear as long I find interesting information concerning the topic resp. my questions (but I don't use tablet/smartphone) !
Here we go (for me the best known approach) - only in German. If you want to read it in English, ask there:
vertrieb@fsm.ag
Most easy approach are a 1000W halogen floodlight and two main rocker light switches for heavy loads.
One switch for "switch-on" with halogen floodlight in series to the load and second switch for shorting this halogen floodlight after it gets dark (this happens after the magnetic field from the transformer has built up).
A friend of me turns on four Krell KSA250 power amplifiers simultaneously without any trouble.
If the halogen floodlight is short-circuited with the second switch while switched on with the first switch, the house fuse will trip.
Thus there is no need to worry about safety requirements.
If you want links concerning halogen floodlights and appropriate switches, use google (for you I don't post any link from now on).
vertrieb@fsm.ag
Most easy approach are a 1000W halogen floodlight and two main rocker light switches for heavy loads.
One switch for "switch-on" with halogen floodlight in series to the load and second switch for shorting this halogen floodlight after it gets dark (this happens after the magnetic field from the transformer has built up).
A friend of me turns on four Krell KSA250 power amplifiers simultaneously without any trouble.
If the halogen floodlight is short-circuited with the second switch while switched on with the first switch, the house fuse will trip.
Thus there is no need to worry about safety requirements.
If you want links concerning halogen floodlights and appropriate switches, use google (for you I don't post any link from now on).
Hi tiefbassuebertr,
Just lost my entire post due to a link. See what I mean?
Okay, here goes again. You actually think putting a 1,000 watt floodlight in series is reasonable? Then having to operate another switch to short them out? Really? All solutions presented previously require no user intervention past turning the unit on. I fail to see how this is superior in any way.
The other units for inrush current limiting you posted are more complicated than they need to be as well. It's okay to bring attention to alternative ways of doing this, but to claim they are superior is, I think, completely unreasonable.
Krell amplifiers can draw a lot, but incorporate their own inrush current limiting. I know because I work on them. So knowing this, why is your friend doing this to begin with? Actually, I do not want to know.
-Chris
Just lost my entire post due to a link. See what I mean?
Okay, here goes again. You actually think putting a 1,000 watt floodlight in series is reasonable? Then having to operate another switch to short them out? Really? All solutions presented previously require no user intervention past turning the unit on. I fail to see how this is superior in any way.
The other units for inrush current limiting you posted are more complicated than they need to be as well. It's okay to bring attention to alternative ways of doing this, but to claim they are superior is, I think, completely unreasonable.
Krell amplifiers can draw a lot, but incorporate their own inrush current limiting. I know because I work on them. So knowing this, why is your friend doing this to begin with? Actually, I do not want to know.
-Chris
I agree it’s complex - it’s like a SMPS PMC but inductive load and empty caps which means spreading the load over the entire incoming sine wave in a controlled form.
i’m wondering if a concept of building the flux with aux winding is another option - yet gain complex.
May be a ladder of PTCs on a sequential switch - so each power on trips to the next cold PTC, once the last PTC is used the switching resets or locks out.
I’ve used PTCs with 5 parallel torroidal transformers with a manual bypass but really need to make that automated.
Hi Nick,
Sounds ever more complicated!
Sure you can do this, but what is wrong with a resistive element that achieves the goal in a simple, straight forward manner?
The problem is, each burst of energy creates a high peak current through the rectifiers and filter capacitors. Look at rectifier repetitive peak current ratings and think about what you are doing.
Great thought experiment though.
-Chris
Sounds ever more complicated!
Sure you can do this, but what is wrong with a resistive element that achieves the goal in a simple, straight forward manner?
The problem is, each burst of energy creates a high peak current through the rectifiers and filter capacitors. Look at rectifier repetitive peak current ratings and think about what you are doing.
Great thought experiment though.
-Chris
Hi altec9440,
Good article (see, I read them).
I disagree with high temperature solder. Properly used they do not get excessively hot, and a fixed resistor is removed from the circuit by short. For an NTC resistor - yes they run warm to very warm. However you would normally mount them to a terminal strip instead of a PCB. That allows the body to run hotter (you want this) and the connections to run not as hot. Yes, leave some length on the leads.
If you mount an NTC resistor for inrush limiting on a PCB with short leads, you will over time cook the board. It will affect the solder joints even with high temperature solder. That is unless you short it out after a brief time, and then you may as well use a fixed resistor. The only time these parts get hot and may burn out is when the relay drops out due to a fault, and at that point they probably saved you from more damage in the circuitry drawing current. So let them burn in fault conditions and plan for that to happen. Normal operation should not make a fixed resistor that gets shorted out ever get hot. Not unless you pick an excessively long time interval (normally 1/2 a second - ish).
-Chris
Good article (see, I read them).
I disagree with high temperature solder. Properly used they do not get excessively hot, and a fixed resistor is removed from the circuit by short. For an NTC resistor - yes they run warm to very warm. However you would normally mount them to a terminal strip instead of a PCB. That allows the body to run hotter (you want this) and the connections to run not as hot. Yes, leave some length on the leads.
If you mount an NTC resistor for inrush limiting on a PCB with short leads, you will over time cook the board. It will affect the solder joints even with high temperature solder. That is unless you short it out after a brief time, and then you may as well use a fixed resistor. The only time these parts get hot and may burn out is when the relay drops out due to a fault, and at that point they probably saved you from more damage in the circuitry drawing current. So let them burn in fault conditions and plan for that to happen. Normal operation should not make a fixed resistor that gets shorted out ever get hot. Not unless you pick an excessively long time interval (normally 1/2 a second - ish).
-Chris
Hi Chris,
agree with you on this point, even if industry adopt this method.
a calculator may be of interest:
https://www.ametherm.com/blog/inrush-current/calculate-inrush-current-three-steps
agree with you on this point, even if industry adopt this method.
a calculator may be of interest:
https://www.ametherm.com/blog/inrush-current/calculate-inrush-current-three-steps
Krells own soft start unit was removed on all three devices due not reliable operation (bad design from my view) - go to
https://forum.polkaudio.com/discussion/171267/krell-ksa-250-soft-start-resistor-relocation
Having to operate another switch to short flootlight out isn't a really disadvantage (please note: three KSA250 devices switch on at the same time - in case of correct working build-in soft start unit would be three switches to press - now there are only two).
Works perfect without any trouble since very long time.
In case of replace the another switch by a relay (actually not really an issue) is to be accepted that it will also become more complicated again.
I happen to know Krell's design is solid. Fixed a few in my time. Not everything is perfect, but this one isn't bad at all.
It is dangerous when you condemn a good design and install something that isn't. You consider yourself a better designer?
You didn't read my comments above obviously. I don't like Krell amps, but the design stood the test of time without many failures. It seems many folks decide they know better, and publish their ideas. That doesn't make them right.
It is dangerous when you condemn a good design and install something that isn't. You consider yourself a better designer?
You didn't read my comments above obviously. I don't like Krell amps, but the design stood the test of time without many failures. It seems many folks decide they know better, and publish their ideas. That doesn't make them right.
That’s exactly my point on safety, do you think such a situation would pass regulatory approval?
That’s why the pioneer design has a thermal fuse under the big 20w resistor so that the circuit opens under the fault condition with out frying a circuit board.
Hi Rick,
Yes, thermal fuses are effective. However I have seen many products in the past where the resistor simply burns open and they were CSA approved as well. Todays regulations? Who knows, but if the part is isolated and will not burn anything else it should be okay. Really. the fuse should have opened anyway.
Use common sense. Adding a thermal fuse adds a layer of safety - so why not?
Yes, thermal fuses are effective. However I have seen many products in the past where the resistor simply burns open and they were CSA approved as well. Todays regulations? Who knows, but if the part is isolated and will not burn anything else it should be okay. Really. the fuse should have opened anyway.
Use common sense. Adding a thermal fuse adds a layer of safety - so why not?
Hi Chris
Correct, something has to burn open under the fault condition, hopefully it’s a cheap and easily replaced part, does not cause any smoke, might not be for what caused the fault in the first place. I am sure you have seen enough of them in your time to know what and what does not work well.
Correct, something has to burn open under the fault condition, hopefully it’s a cheap and easily replaced part, does not cause any smoke, might not be for what caused the fault in the first place. I am sure you have seen enough of them in your time to know what and what does not work well.
lol!
To say the least!
I have seen enough surge resistors burn open without causing any additional damage to surrounding materials to be totally unconcerned with the possibility. But in every case, these were positioned with some thought to this happening. Also, resistors (cement types) do not cause open flame, they may smoke (good) and get extremely hot, but mounted properly this is not an issue. Emitter resistors are another component that can do exactly the same thing, yet you don't see anyone getting excited about those, now do you?
To say the least!
I have seen enough surge resistors burn open without causing any additional damage to surrounding materials to be totally unconcerned with the possibility. But in every case, these were positioned with some thought to this happening. Also, resistors (cement types) do not cause open flame, they may smoke (good) and get extremely hot, but mounted properly this is not an issue. Emitter resistors are another component that can do exactly the same thing, yet you don't see anyone getting excited about those, now do you?
Hi Chris, what is wrong from your view concerning the described design in post #44 resp. which safety requirements are violated ?
I would say, I choice clearly the better soft start design than Krell - independent from this - this design isn't from me, nevertheless very good and the least complicated that is possible.
Your previous opinion was only "That's a disaster that two switches have to be pressed for switch-on" - if I interpret this correctly in your post #45.
Hi tiefbassuebertr,
Okay, stop right there!
You did not quote me properly at all and I had to look back to check. Wasting my time. If you are going to quote someone, do it accurately without changing their meaning.
I didn't say that, period. You just put words in my mouth and I do not like it, plus it is really a lie. Be honest, quote accurately and in context so you do not change the meaning. Right now I know I cannot trust anything you "quote" from another member or maybe even another web site. You just proved that .
I'll advise readers to disregard tiefbassuebertr's post above and regard what he says with caution. Read earlier to get the true story.
Your earlier suggestion of 1,000 watt floodlights seems unsafe, bulky and probably not nearly as effective as a resistor since the cold filament resistance of a lamp is extremely low - resulting in high inrush current. Only someone who doesn't understand how things work would even try that. It is not intelligent.
Now, your personal opinions on someone else's design are your own, and that is fine. But I say again, Krell's design works in their entire line and has for years. It is not a weakness in design, but all circuits will examples that fail over a long period of time. You know what the main issue is? The relay contacts. No kidding! Relays, just in case you were not aware are maintenance items, like switches can be. You are expected to replace relays occasionally. Very common in industry, common on the electronics service bench.
I'll bet your examples fail in a similar way over time once you get enough out there over a similar time period.
-Chris
Okay, stop right there!
You did not quote me properly at all and I had to look back to check. Wasting my time. If you are going to quote someone, do it accurately without changing their meaning.
I didn't say that, period. You just put words in my mouth and I do not like it, plus it is really a lie. Be honest, quote accurately and in context so you do not change the meaning. Right now I know I cannot trust anything you "quote" from another member or maybe even another web site. You just proved that .
I'll advise readers to disregard tiefbassuebertr's post above and regard what he says with caution. Read earlier to get the true story.
I never said safety requirements were violated. Not once. I said they were more complicated than they need be, that's all.
Your earlier suggestion of 1,000 watt floodlights seems unsafe, bulky and probably not nearly as effective as a resistor since the cold filament resistance of a lamp is extremely low - resulting in high inrush current. Only someone who doesn't understand how things work would even try that. It is not intelligent.
Now, your personal opinions on someone else's design are your own, and that is fine. But I say again, Krell's design works in their entire line and has for years. It is not a weakness in design, but all circuits will examples that fail over a long period of time. You know what the main issue is? The relay contacts. No kidding! Relays, just in case you were not aware are maintenance items, like switches can be. You are expected to replace relays occasionally. Very common in industry, common on the electronics service bench.
I'll bet your examples fail in a similar way over time once you get enough out there over a similar time period.
-Chris
Only a couple of days ago, I received a Manley Stingray. Should have bought one years ago for my tastes. Anyway, something that I noticed is that when the amp is first turned on, the filaments light up as quick as a light bulb. this doesn't seem right to me. IIRC past tubes amps had a little time (a second or two) pass before the filaments started glowing. So, my question would be about the need of some sort of current limiting at start up or is this normal?
