APC S15 Specifications download pdf (Page 8)

Things got a little more complicated when I upgraded my power amplifiers to a seven-channel Theta Digital Dreadnaught

II. While the Dreadnaught II is a wonderful sounding amplifier, I love it, it loves AC power – 295 watts at idle and 160

watts in the standby mode.

The “greener” side of me could not handle having 160 watts “on” 24/7, so I decided I had to switch it on and off, as I had

with my previous amplifiers. Although the Adcom’s “Amplifier” outlets were rated for “750 watts continuous and even

greater in-rush surges on amplifier turn on”, its relay blew out the first time I tried to switch the Theta. A replacement

relay blew just as quickly. As I said, the Theta likes AC power, especially when first turning on! The fact that it also

tended to momentarily dim the lights in the house was probably a clue. So I used a relay in the Adcom to switch on and

off a 60-amp contactor that switched the power to the Theta. Complicated, yes, but it again it worked.

So when considering integrating the S20 into my system, I was suspicious that the Theta amplifier might be too much

for it. “No problem” my contract at APC assured me, and he was certainly right. (and I was assured the S15 would be OK

as well). Once I had the S20, it literally installed in minutes. No extra relays, contactors, etc. It was plug and play with

the one exception noted below.

I was very pleased to find that indeed. the S20 did handle the rush of current when the Theta amplifier turned on; and

actually the way the APC handles the Theta amplifier is quite instructive. As the amplifier turns on, the APC sees the

line voltage start to drop below 100 volts and immediately switches to “battery” mode where the battery momentarily

supplies the current surge, not the AC line input. This is likely much better for all the other components in the system

that therefore see a much a more continuous line voltage without the sag in voltage that would occur if the current from

battery was not available.

I think of the APC S Type Power Conditioners as very much like hybrid cars where current from batteries are used to

augment power in cases where the operator’s demand for power exceeds the power available from the gasoline engine. And

of course, with hybrids when available power exceeds demand, the batteries are being charged, ready for the next need for

their power. Fortunately switching from battery charging to battery power augmentation happens very quickly and

seamlessly with power to the wheels at any given moment coming from the gas engine, the battery or both. (I’ve owned

two hybrids now and they are great!)

The APC S Type Power Conditioners work in a similar way to hybrid cars in that they are Line Interactive rather than

Standby systems.

In Line Interactive UPS systems the battery-to-AC power converter (inverter) is always connected to the output and

instantly available to cover unusual short-term power needs, as well as power failures.

In practice the S20 goes into “Battery” every time I turn the system on, as the turn on current demanded by the Theta

amplifier is more than my wall outlet can supply without considerable voltage sag. I have also seen the “Battery” light go

on momentarily on a number of other occasions (there is also a beep I could turn off). I am not sure whether it is the well

pump, the spa pump, the washing machine, some combination of the above, or a more global power sag.

Unfortunately such events are not that uncommon in this household, and would indicate a sag below 100V for at least a

brief period of time. The S20 also goes into the Voltage regulation mode much of the day indicating the line voltage has

dropped below approximately 115V.

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APC S15 Specifications Page 8