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RE: AccuVote-TS power-related questions
Ian S. Piper
Diebold Election Systems,
Numerous AccuVote-TS units
configured in daisychain formation in the DeKalb County (amongst others) in
the Georgia elections received insufficient AC power, despite being connected
to AC power. Units not daisychained apparently
did not experience these problems.
[Ian S. Piper] I
don't think you have enough information to support your conclusion.
Although details are rather scarce immediately after an election, it
would be useful to get more info on the situation to determine what really
happened. Info such as,
- Where were the voting centers where
this problem occurred.
- What are the serial numbers of
the units that experienced the problem.
- Was the power connection from the booth to the unit
secure in each case?
- Were those cables were tested to ensure that they were
connected inside the
BTW: What is meant by "insufficient
- What effect would power cable length,
configuration, shielding, or any other cabling characteristics have on the integrity of power
delivery in the context
[Ian S. Piper] Our power supply is a wide
ranging type that can operate on an AC voltage as low as 80Vac. The
cable lengths used in elections wouldn't be an issue, unless they went to
ridiculous extremes. Personally, I'd limit extension cord lengths
to a total of 100 feet per daisy chain and I'd use a heavy wire gauge
- How much power is lost from the power transferring
through the AccuVote-TS unit itself?
Piper] There is no power lost; it is consumed. Power is
determined by voltage and current. The voltage
is constant between machines. Each unit would consume anywhere
from 0.4 Amps (Idle with a fully charged battery) up to 1.5 Amps (Fast
charging a flat battery).
- What is the ceiling number of units that may be
daisychained from one power outlet?
Piper] The limit on current is 10 Amps as would be dictated by the
circuit breaker on the first booth of the daisy chain. As we don't
know how many units in a daisy chain have charged or
discharged batteries, we have to assume the worst, which is
that each unit is drawing the most current possible (1.5 Amps while
fast charging a flat battery). With a 10 Amp circuit breaker on the
first booth, it can supply 1.5 Amps to up to 6 units in a chain. If
the units aren't fast charging you could do more, but in a situation
where the AC power is out in the whole building and the batteries
are used to a flat condition, when the AC power comes back up, you'd have
all the units fast charging and drawing up to 1.5 Amps each.
Therefore, you'd want to stick to the 6 unit limit on a daisy
NOTE: When the units are turned off and charging a battery, the
worst case is a 1 Amp current draw, so therefore 10 units can be daisy
chained in a warehouse charging setting.
- What power cabling may be used, other than our own
[Ian S. Piper] The customer can use
extension cords and power bars to deliver power to the units as long as they
are rated to carry at least 10 Amps. Our power cables are rated
for 10 Amps.
- Is it the case that in order to
not overload the power drawn from a single power jack, the jack should be
connected exclusively to a power circuit, ie. the circuit should service no
more than that power jack. Would there be any simple tool (other than
a voltmeter) available that could determine that a power jack is connected
exclusively to a power circuit?
[Ian S. Piper] You don't need to have a
dedicated circuit for the outlet that the daisy chain is attached to.
Even if there are more outlets on that circuit, the answer is "don't use
There's no simple tool to determine that an outlet
is isolated from others. An electrician can make that determination
using some tools that put a frequency on the circuit and sensing which
devices (lighting or other outlets) share that circuit. Other
than that, the old "turn the breaker off and see what is not working"
approach is simple enough to determine what is on the
circuit. Power capacities should be part of the survey
at each vote center.