With the Sencore
PR57 supplying AC power to
the UPS, we'll adjust the voltage from 120VAC up to 140VAC to simulate a spike in the utility power supply.
When the Powerware 5125 cuts itself off from this input and switches to its alternate source,
we'll be monitoring what happens to the output voltage as the UPS strives
to compensate.
With a computer running off the UPS, we'll use the digital
multimeter to measure the voltage level, and more importantly, where the output voltage dips during the switching
process. The switch from AC to battery power occurs rapidly, but not instantaneously... If the output voltage dips
too low for too long, it can cause instability in a sensitive power suppy and disrupt the computer. According
to Powerware, the typical transfer time for the 5125 UPS is on the
order 2-4ms.
 |
|
UPS Output Voltage & Variable
Utility Supply (+/- 3%) |
Under-Voltage
Trip Points: |
Over-Voltage
Trip Point: |
Lowest Output Voltage: |
|
| |
50V |
60V |
70V |
80V |
90V |
100V |
110V |
115V |
120V |
130V |
140V |
Utility VAC |
|
| Powerware 5125 |
120 |
120 |
120 |
120 |
114 |
112 |
108 |
115 |
120 |
114 |
124 |
124 |
110, 95, 85 |
127 |
107 |
|
| Belkin 1000VA |
102 |
102 |
102 |
102 |
107 |
117 |
127 |
115 |
120 |
128 |
98 |
122 |
110, 90 |
135 |
98 |
|
| No UPS. |
- |
- |
- |
80 |
90 |
100 |
109 |
115 |
120 |
130 |
- |
123 |
- |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Test Observations: The Powerware 5125 1000VA UPS output
voltage fluctuated during the 90V utility under voltage trip point from between 106-119VAC as a
mechanical relay moved the test load (computer) from one power circuit to another. The lowest
we saw UPS output voltage reach was just prior to an
under voltage trip point, at about 86VAC Utility Input, where the UPS
was momentarily delivered an output of 107VAC to the computer.
Throughout the variable utility supply
tests, the computer remained powered on, and did not restart. Most APFC
power supplies are rated for operation with between 90V-240V, and more common
PFC power supplies (where the user must select 115V/220V) are able to
make do with as low as a 100VAC utility supply.
Conclusions
The Powerware
5125 1000VA uninterruptable power supply certainly offers up an advanced set
of management features that make it ideal for use in a networked environment,
with both desktop and workstation computers. The expandable X-slot comes stock
with a serial port allowing terminal communication with the UPS, but from
what we've seen, really thrives when the SNMP/Web adaptor option is
installed. The statistical tracking, and event actions allow the Powerware 5125
to be customized to take different reactionary procedures based on a total
power loss scenario. From sending OS shutdown commands to client computers loaded
with the Netwatch, to simply shutting down an unnecessary load segment, or
emailing an administrator a status report, the versatility is there.
The control console
on the front of the Powerware 5125 gives users at-a-glance status
indicators of power quality, battery, output load, and a few other
relevant parameters. A hot swapable battery pack and option to increase power capacity with
up to four external EBMs further add to the list of compelling features
for 5125 UPS. For home users, the noisy cooling fan quickly
becomes distracting, but otherwise we generally found the Powerware 5125
1000VA easy to use, and configure.
Battery life tests were identical to other 1000VA UPS
we tested, and for an estimated 300VA load (typical 19" monitor and 2GHz
Pentium 4 computer), supplied 23 minutes of useable time after
the power was cut. Unlike the Belkin Universal 1000VA UPS used
in that comparison however, there was a noticeable lack of hum
from the inverter in the 5125.
During variations
with utility power to simulate brown outs, or voltage spikes, there were a
few points were the output power dipped down to 107VAC
momentarily during a switching event. Some especially sensitive devices may be
disrupted by this, but during these fluctuations the test computer system
remained operational and did not restart.
All in all, when shopping for a
good UPS there are plenty of variables to consider, and
with a price of about $280USD ($370CDN) , the Powerware 5125 1000VA UPS certainly presents a very compelling case for itself. I think
if you intend to run one or more networked PCs off a 1000VA power supply, and
are looking for good management options to tide you through the occasional
brown out or power outage without a scratch, the Powerware 5125 is an
excellent candidate to consider!
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