??? Why Non Current Limiting Surge Protection ???

@freediver 

I agree with your ohms law analogy but it’s the high overvoltage event that causes the damage to the electronic components in the equipment.  Example, if you fed a 120V power amp with 240V the higher voltage is what would fry the amp.

FWIW the majority of surge protection devices are designed to clamp, divert, high voltage transients lasting for only microseconds to a millisecond in duration. A sustained high overvoltage will fry MOVs. So why do most SPDs manufacturers use MOVs? Because then can react within a nano second or less. And SPDs that use multiple MOVs in their construction will meet UL 1449 3rd Edition lab testing and therefore are UL Listed/certified. Watch out for SPDs that say it meets UL standards. Meets does not equal Listed/certified.

Series mode SPDs are a different type of SPD animal in the way they work. Do they react in a nano second or less? Are they UL 1449 3rd addition.UL Listed/Certified?  

Some reading material on SPDs.

https://www.nemasurge.org/faqs/ 

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https://www.nemasurge.org/ul-1449-transient-voltage-surge-suppressors/

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https://www.nemasurge.org/how-spd-s-work/

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https://www.eaton.com/content/dam/eaton/services/eess/eess-documents/sa01005003e.pdf

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As for this:

I can’t see it affecting a power amplifiers SQ if it’s not functioning..

The power amplifier would never know if the SPD was doing its’ job or not. A UL1449 3rd Edition UL Listed SPD reacts to a high voltage transient in one nano second or less. 

What a power amplifier will react to is a fluctuating voltage drop condition caused by a power conditioner’s inability to supply a steady state voltage. 

Example:

2x200W amp might take from mains close to 1kW during peaks. The problem is that peak supply current won’t be expected 8A, but rather close to 40A. It is because current is drawn only for very short time (millisecond pulse) at the peak of full wave rectified sinewave. It applies to most of LPS. Power delivered with such short pulses not only creates larger voltage drops in house wiring, but also heat-up amp’s power transformer, that has to be oversized (higher copper losses and higher core losses for eddy currents and hysteresis).
 

https://electronics.stackexchange.com/questions/329443/current-through-the-smoothing-capacitor-in-bridge-rectifier

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Please explain what happens if the power transformer’s secondary winding voltage is lower feeding the rectifier, due to a quick AC mains VD event, and the electrolytic capacitors voltage is higher. Just going from memory the rectifier will not conduct and the caps do not get recharged for that "(millisecond pulse)" in time.

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@jea48   You are right - there will be no current thru rectifiers until capacitor voltage will drop below rectifier supplied peak voltage.  Theoretically it is possible to build LPS where capacitors keep average instead of peak voltage, but it requires huge inductor in series (in order of Henries) made with thick wire and AFAIK nobody is doing it.  One problem is lower rail voltage (average instead of peak) while the other is dependency on the load current.

http://www.r-type.org/articles/art-144.htm

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When the amplifier is plugged directly into the wall outlet the only thing that will cause VD at the outlet is the size and length of the branch circuit wiring. A 20A circuit breaker will easily pass 40amps of short quick draws of 40 amps of current all day long without tripping.. 

How about the power conditioner you are looking at? Will it supply a steady state AC voltage feeding a power amp? 

 

@jea48 Yea that thread is why I posted this..To me it makes sense to want current limiting during a surge since the load stays the same & voltage increases ohms law says current will also increase... .I can’t see it affecting a power amplifiers SQ if it’s not functioning..

I’m confused about this..If current limiting is only applied during a power surge,why are they frowned upon for audio gear?

During a power surge current is not the issue. Voltage is the problem. A high voltage power surge can/will cause damage to electronic equipment.

Are there instances where current limiting is desired? Yes, in big power wattage output power amps. On turn-on/power-on a soft start circuit in series with the primary winding of the amplifier will limit inrush current draw on the branch circuit wiring circuit breaker in the electrical panel. Example, older monster Krell amps used across the AC mains when powered on. The high inrush current would often cause the circuit breaker in the electrical panel to trip. Krell’s solution to the Dealers? Tell the user to install a higher ampere rated circuit breaker in the electrical panel.

Then there is a thread running here on Agon about surge protection power conditioner that won’t limit current to plugged in equipment. I imagine limit current draw of a power amplifier. I asked the OP to explain in more detail what he meant.. No response...

I wanted to make sure the OP wasn’t thinking the surge protection circuitry in a power distributor or power conditioner limited current to the power outlet(s). It doesn’t, or shouldn’t... If there is current limiting it is elsewhere in the design and or materials used in the unit.    

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