More confused than ever about a few products...

[Anonymous user]

I did some searching and now think I may have the wrong product attached to my TV/game system and audio system. Awhile back I purchased a pair of the Line-R1200 units thinking they would be the best choice since the can regulate voltage but as I read more they seem to have a high let through rating? I am wondering now if it wouldn't be smarter to dump these and get some surge protectors that have a rating of 3400 joules and 40v let through rating?
I guess I misunderstood the reason for the Line-r products?

[Anonymous user]

I don't know how APC come up with these low numbers since the lowest value possible using varistors (MOVs) for a 120V outlet, is 330V.

One thing people need to know is that most electronic equipments don't need such a low let-through voltage. Most power supplies withstand voltage surges up to 2000V - normal mode (Phase to Neutral / Phase to Phase), and up to 4000V - common mode (Phase-Ground, Neutral/Ground). The most sensitive electronics withstand voltage surges up to 1500V in normal mode. Computer Power Supplies can withstand 2000V surges repeatedly without any sign of damage or malfunction.You can find these informations on the IEC - International Electrotechnical Comission standards and on ATX Power Supply Design Guides. In the case of ATX PSUs they must withstand 2000V surges indefinately to comply with international standards.

The surge protectors has such low figures because they have to also "try" to protect the equipment when sustained overvoltage happens on the power grid, but when this happen the surge protectors burns itself in order to protect the equipment and then you have to buy another one. Voltage regulators and UPSes work in a different way, they have surge protection bult-in as well, with higher let-through voltages, but.they have also have a relay that isolates your equipments from the power grid when there is a sustained low or high voltage condition in the power grid. The varistors inside them have to withstand the sustained overvoltage events so that it doesn't burn itself and have a long life since 130V varistors have a relatively lower life. A 250V MOV when working on a 120V outlet can last three times as long or more than a 130V MOV. In some environments where there are a large number of voltage surges daily, a 330V let-through voltage surge protector doesn't last more than 3 years, there are reported cases that in 1 year the surge protector is gone, since it shunt all the small surges to neutral/ground "needlessly" and most equipment can withstand much more than 330V by itself. MOVs have a limited lifespan, as more surges it shunts to ground, the shorter will be its lifetime.

The Line-R line is a voltage regulator which means it tries to keep the voltage as close as possible to 120V, when there is a brownout or an overvoltage condition, it step-up the voltage a little bit or step-down a litte bit in order to keep it as close as possible to 120V. It also isolates the equipment from the power grid when the voltage is below or higher its regulation capability. UPSes do the same thing, but they switch to battery mode in order to keep your equipment running. Both of them has surge protection built-in.

Now a days, most electronics can work from 100-240V so there is no need for voltage regulation and those that work at 120V only they usually have a +/- 20% voltage tolerance

Message was edited by: rau

Message was edited by: rau

Message was edited by: rau

[Anonymous user]

Thanks for the detailed response. If I understand your response it sounds like the Line-r product might be fine for my use, just excessive. The audio system is tube so the more stable the input current the better to reduce the chance of strain put on the tubes. I think this is mostly for my peace of mind because I have been watching the input voltage on my ups and it seems to only vary between 119-120.

[voidstar_apc]

Interesting.

>
I don't know how APC come up with these low numbers since the lowest value possible using varistors (MOVs) for a 120V outlet, is 330V.
>

APC's let through rating seems to be calculated as the difference between the effective clamping voltage and the line peak, see here. So a 40V let-through means it clamps at 370V.

[Anonymous user]

First I'd like to apologize for a few english mistake I made on the last message. English is not my first language...

Michael415,

In you case, it is useful to keep the voltage as close to the nominal input voltage of your audio system as possible and regarding the voltage surges, I'm sure the protection provided by the voltage regulator is enough for your system. I'm not saying it is capable of handling a direct lightining strike, few protecttion systems can do that, but for the most common type of surges, il will be enough.
----
Voidstar,

Thanks for the explanation! So yeah, the line peak voltage of a 120V outlet would be something close to 170V, but I think APC should keep using the 330V value on the products specs instead. The use of numbers below that is only good to confuse the layman. The competition in this business is big and each manufacturer wants to show people that their product is better than the products of its competitor so I think APC sometimes uses this as a marketing strategy making people believe a 40V let-though, and sometimes 80V let-through, is better than the 330V spec, which is not true for surge protectors that uses MOVs.They inflate the joules rating, they inflate the kiloAmps rating... and now they're "deflating" the let-through voltage numbers! And even if these numbers were the actual voltage seen at the surge protector outlet after a surge, it would be overkill for 98% of equipments used these days. 330V is overkill already, regarding voltage surges that last a few microseconds. I don't know about the APC UPSes sold in the US, but the ones sold here in my country you usually find 230 to 510V MOVs inside of them.whic have a clamping voltage of 600 to 1500V.

Thank you!

Message was edited by: rau

Message was edited by: rau

Message was edited by: rau

[Anonymous user · Accepted solution]

I did some searching and now think I may have the wrong product attached to my TV/game system and audio system. Awhile back I purchased a pair of the Line-R1200 units thinking they would be the best choice since the can regulate voltage but as I read more they seem to have a high let through rating? I am wondering now if it wouldn't be smarter to dump these and get some surge protectors that have a rating of 3400 joules and 40v let through rating?
I guess I misunderstood the reason for the Line-r products?