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RE: AccuVote-TS power-related questions

Title: Message
Ian, thanks for your information.
See below.
-----Original Message-----
From: owner-support@dieboldes.com [mailto:owner-support@dieboldes.com] On Behalf Of Green, Pat
Sent: November 8, 2002 5:26 AM
To: 'support@dieboldes.com'
Subject: RE: AccuVote-TS power-related questions

For what it's worth, all the units I observed in Alameda were daisy-chained and had no problems.   ...Pat
-----Original Message-----
From: Ian S. Piper [mailto:ian@dieboldes.com]
Sent: Thursday, November 07, 2002 4:38 PM
To: support@dieboldes.com
Subject: RE: AccuVote-TS power-related questions

See below.
Ian S. Piper
Diebold Election Systems, Inc.
-----Original Message-----
From: owner-support@dieboldes.com [mailto:owner-support@dieboldes.com]On Behalf Of Nel Finberg
Sent: Friday, November 08, 2002 4:00 AM
To: support
Subject: AccuVote-TS power-related questions

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 booth?
BTW:  What is meant by "insufficient AC power"? 
Keith, would you be able to respond to Ian's questions?  I don't have the information he has asked for.   
  • What effect would power cable length, configuration, shielding, or any other cabling characteristics have on the integrity of power delivery in the context of daisychained AccuVote-TS units? 
    [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 extension cord.  
Why use a heavy wire gauge extension cord?  Could you be more specific as to power dissipation in terms of cable length and cable gauge?  Are you saying that shielding is not an issue? 
  • How much power is lost from the power transferring through the AccuVote-TS unit itself?
    [Ian S. 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? 
    [Ian S. 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 chain.
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 designated ones?
    [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 them." 
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.