Chapter 6: General Core Requirements

6.1 General Design Requirements

Note: The ballot counter requirements from [VVSG2005] have been converted into functional requirements (Part 1: 4.3.5 “Ballot counter”).

6.2 Voting Variations

The purpose of this formulaic requirement is to clarify that support for a given voting variation cannot be asserted at the system level unless device-level support is present. It is not necessarily the case that every device in the system would support every voting variation claimed at the system level; e.g., vote-capture devices used for in-person voting may have nothing in common with the vote-capture devices (typically MMPB) used for absentee voting. However, sufficient devices must be present to enable satisfaction of the system-level claim.

6.3 Hardware and Software Performance, General Requirements

This section contains requirements for hardware and software performance:

• Reliability;
  
• Accuracy/error rate;
  
• Misfeed rate; and
  
• Electromagnetic Compatibility.

6.3.1 Reliability

The following sections provide the background and rationale for the reliability benchmarks appearing in Part 1: 6.3.1.5 “Requirements”. Given that there is no "typical" volume or "typical" configuration of voting system with such diversity among the many jurisdictions, it is nevertheless necessary to base the benchmarks on some rough estimates in order that they may be in the correct order of magnitude, albeit not optimal for every case.

6.3.1.1 Classes of equipment

Because different classes of voting devices are used in different ways in elections, the kinds of volume against which their reliability is measured and the specific reliability that is required of them are different. The classes of voting devices for which estimates are provided are listed below. Please refer to the definitions of the parenthesized terms in Appendix A.

• Central-count optical scanner (CCOS)
  
• Election Management System (EMS)
  
• Precinct-count optical scanner (PCOS)
  
• Direct Recording Electronic (DRE)
  
• Electronically-assisted Ballot Marker (EBM)
  
• Ballot activator (activation device)
  
• Audit device (Audit device)

6.3.1.2 Estimated volume per election

The "typical" volumes described below are the volumes that medium-sized jurisdictions in western states need their equipment to handle in a high turn-out election, as of 2006. A county of 150 000 registered voters will have 120 000 ballots cast in a presidential election. A typical polling place will be set up to handle 2000 voters, which equals 60 polling places in a mid-sized county.
Central-count optical scanner: Medium-sized jurisdictions in western states need their central count equipment to scan 120 000 ballots in an election. Depending upon the actual throughput speeds of the scanners, they use 2 to 8 machines to handle the volume. "Typical" volume for a single scanner is the maximum tabulation rate that the manufacturer declares for the equipment times 8 hours.

Election Management System: The volume equals the total number of interactions with the vote gathering equipment required by the design configuration of the voting system to collect the election results from all the vote-capture devices.

The typical constant across the systems is that the Election Management System will interact once with each polling place for each class of equipment. Assuming our "typical" county with 60 polling places, one or more DREs in each polling place, and one or more optical scan devices, that totals 2×60=120 transactions per election.

The primary differences in the central count EMS environment are whether the optical scan devices are networked with the EMS or function independently.

In the networked environment, the device will interact with the EMS once per batch (typically around 250 ballots). So, 120 000/250=480 interactions.

In the non-networked environment, the results are handled similar to the polling place uploads. Results are copied off to media and uploaded to the EMS. Since central counting typically occurs over several days – especially in a vote-by-mail environment – the test should include several uploads from each scanner. 2 scanners × 4 days = 8 uploads.

To simplify these different cases to a single benchmark, we use the highest of the volumes (480 transactions), which leads to the lowest failure rate benchmark.

Precinct-count optical scanner: Polling place equipment has a maximum number of paper ballots that can be handled before the outtake bins fill up. Usually around 2500.

Direct Recording Electronic: Typical ballot takes 3–5 minutes to vote, so the most a single DRE should be expected to handle are 150–200 voters in a 12 hour election day.

Electronically-assisted Ballot Marker: Typically takes longer to vote than with a DRE. An individual unit should not be expected to handle more than 70 voters on election day.

Ballot activator: The volume use of these devices match the volumes for the polling place, which in our assumed county is 2000/polling place. Our assumed county would have 10–14 DREs/polling place with around 20 tokens. Each token would be used about 100 times.

Audit device: No information available.

The estimated volumes are summarized in Part 1: Table 6-1 . The estimates for PCOS and CCOS have been generalized to cover precinct tabulator and central tabulator respectively, and a default volume based on the higher of the available estimates has been supplied for other vote-capture devices that may appear in the future. Audit devices are assumed to be comparable to activation devices in the numbers that are deployed.

6.3.1.3 Manageable failures per election

The term failure is defined in Appendix A. In plain language, failures are equipment breakdowns, including software crashes, such that continued use without service or replacement is worrisome to impossible. Normal, routine occurrences like running out of paper are not considered failures. Misfeeds of ballots into optical scanners are handled by a separate benchmark (Requirement Part 1: 6.3.3-A), so these are not included as failures for the general reliability benchmark.

The following estimates express what failures would be manageable for a mid-sized county in a high-turnout election. Medium-sized counties send out troubleshooters to polling places to replace or resolve problems with machines.

Any failure that results in all CVRs pertaining to a given ballot becoming unusable or that makes it impossible to determine whether or not a ballot was cast is called disenfranchisement. It is unacceptable for even one ballot to become unrecoverable or to end up in an unknown state. For example, an optical scanner that shreds a paper ballot, rendering it unreadable by human or machine, is assessed a disenfranchisement type failure; so is a DRE that is observed to "freeze," providing no evidence one way or the other whether the ballot was cast, when the voter attempts to cast the ballot.

Central-count optical scanner: No more than one machine breakdown per jurisdiction requiring repairs done by the manufacturer or highly trained personnel. Medium sized jurisdictions plan on having one backup machine for each election.

Election Management System: This is a critical system that must perform in an extremely time sensitive environment for a mid-sized county over a 3 to 4 hour period election night. Any failure during the test that requires the manufacturer or highly trained personnel to recover should disqualify the system. Otherwise, as long as the manufacturer's documentation provides usable procedures for recovering from the failures and methods to verify results and recover any potentially missing election results, 1 failure is assessed for each 10 minutes of downtime (minimum 1 – no fractional failures are assessed). A total of 3 or more such failures disqualifies the system.

Precinct-count optical scanner: A failure in this class of machine has a negligible impact on the ability of voters to vote in the polling place. No more than 1 of the machines in an election experience serious failures that would require the manufacturer or highly trained personnel to repair (e.g., will not boot). No more than 5 % of the machines in the election experience failures that require the attention of a troubleshooter/poll worker (e.g., memory card failure).

Direct Recording Electronic and Electronically-assisted Ballot Marker: No more than 1 % of the machines in an election experience failures that would require the manufacturer or highly trained personnel to repair (e.g., won't boot) and no more than 3 % of the machines in an election experience failures that require the attention of a troubleshooter (e.g., printer jams, recalibration, etc.).

Ballot activator: The media/token should not fail more than 3 % of the time (the county will provide the polling place with more tokens than necessary). No more than 1 of the devices should fail (the device will be replaced by the county troubleshooter).

Audit device: No information available. If comparable to ballot activators, there should be at least 1 spare.

The manageable failure estimates are summarized in Part 1: Table 6-2 . A "user-serviceable" failure is one that can be remedied by a troubleshooter and/or election official using only knowledge found in voting equipment user documentation; a "non-user-serviceable" failure is one that requires the manufacturer or highly trained personnel to repair.

Please note that the failures are relative to the collection of all devices of a given class, so the value 1 in the row for central tabulator means 1 failure among the 2 to 8 central tabulators that are required to count 120 000 ballots in 8 hours, not 1 failure per device.

6.3.1.4 Derivation of benchmarks

We focus on one class of device and one type of failure at a time, and we assume that each failure is followed by repair or replacement of the affected device. This means that we consider two failures of the same device to be equivalent to one failure each of two different devices of the same class. The sense of "X % of the machines fail" is thus approximated by a simple failure count, which is X/100 times the number of devices. This then must be related to the total volume processed by the entire group of devices over the course of an election in order to determine the number of failures that would be manageable in an election of that size.

To reduce the likelihood of an unmanageable situation to an acceptably low level, a benchmark is needed such that the probability of occurrence of an unmanageable number of failures for the total volume estimated is "acceptably low." That "acceptably low level" is here defined to be a probability of no more than 1 %, except in the case of disenfranchisement, where the only acceptable probability is 0.

Under the simplifying assumption that failures occur randomly and in a Poisson distribution, the probability of observing n or less failures for volume v and failure rate r is the value of the Poisson cumulative distribution function,

Consequently, given ve (the estimated total volume) and ne (the maximum manageable number of failures for volume ve), the desired benchmark rate rb is found by solving P(ne,rbve)=0.99 for rb. This sets the benchmark rate such that there remains a 1 % risk that a greater number of failures would occur with marginally conforming devices during an election in which they collectively process volume ve. In the case of disenfranchisement, that risk is unacceptable; hence the benchmark is simply set to zero.

6.3.1.5 Requirements

6.3.2 Accuracy/error rate

Since accuracy is measured at the system level, it is not necessary to define different benchmarks for different classes of devices.

Other accuracy-related requirements include Requirement Part 1: 6.4.1.7-D, Requirement Part 1: 7.1-E, Requirement Part 1: 7.1-F, Requirement Part 1: 7.5.4-A, and Requirement Part 1: 7.8.3.1-B.

6.3.3 Misfeed rate

6.3.4 Electromagnetic Compatibility (EMC) immunity

The International Electrotechnical Commission (IEC) Technical Committee 77 on Electromagnetic Compatibility has defined [ISO95a] the concept of “ports” as the interface of an electronic device (“apparatus”) with its electrical and electromagnetic environment, as illustrated in Part 1: Figure 6-1. In the sketch, the arrows point toward the apparatus, but in a complete assessment of the compatibility, one should also consider the other direction – that is, what disturbances (“emissions”) can the apparatus inject into its environment.

Figure 6-1 Electrical and electromagnetic environment

Five of these ports involve conducted disturbances carried by metallic conductors, and the sixth, the “enclosure,” allows radiated disturbances to impinge on the apparatus. In this context, the term “enclosure” should not be understood as limited to a physical entity (metallic, non metallic, totally enclosed or with openings) but rather be understood as simply the route whereby electromagnetic radiations couple with the circuitry and components of the apparatus.

In previous voting systems guidelines, possible interactions and immunity concerns have been described but perhaps not in explicit terms relating them to the concept of ports. In this updated version of the VVSG, the recitation of compatibility requirements is structured by considering the ports one at a time, plus some consideration of a possible interaction between ports:

1. Power port – also described as “power supply” – via ordinary receptacles of the polling place
2. Earth port – implied in the National Electric Code [NFPA05] stipulations for dealing with the power supply of the polling place
3. Signal port – connection to the landline telephone of the polling place to the central tabulator
4. Control port – inter-system connections such as voting station to precinct tabulator
5. Enclosure port – considerations on immunity to radiated disturbances and electrostatic discharge
6. Interaction between signal port and power port during surge events

Note: In this EMC section, the specified voltage and current levels are expressed in root mean square (rms) for power-frequency parameters and in peak value for surges and impulses.



6.3.4.2 Steady-state conditions

Adequate operation of an eventual surge-protective device and, more important, safety considerations demand that the power supply receptacles be of the three-prong type (Line, Neutral, and Equipment Grounding Conductor). The use of a “cheater” adapter for older type receptacles with only two-blade capacity and no dependable grounding conductor should be prohibited. Details on the safety considerations are addressed in Part 1: 3.2.8.2 “Safety”.


The requirement of using a dedicated landline telephone service should also be satisfied for polling places.


Steady state conditions of a polling place are generally out of the control of the local jurisdiction.


However, for a polling place to ensure reliable voting, the power supply and telephone service need to be suitable for the purpose. Compliance with the National Electrical Code [NFPA05] is assumed to be required.


6.3.4.2-A Power supply – energy service provider

To obtain maximum flexibility of application, the voting system SHALL be powered by a 120 V, single phase power supply, as available in polling places, derived from typical energy service providers.

Applies To: Electronic device

Test Reference: Part 3: 3.1 “Inspection”

DISCUSSION

It is assumed that the AC power necessary to operate the voting system will be derived from the existing power distribution system of the facility housing the polling place. This single-phase power may be a leg of a 120/240 V single phase system, or a leg of a 120/208 V three-phase system, at a frequency of 60 Hz, according to the limits defined in [ANSI06], and premises wiring compliant with the [NFPA05], in particular its grounding requirements.

Source: [NFPA05]


6.3.4.2-B Telecommunications services provider

To avoid compromising voting integrity (accidentally or intentionally), the telephone connection of a voting system SHALL use a dedicated line (no extensions on the same telephone number) and be compatible with the requirements of the telephone service provider.

Applies To: Electronic device

Test Reference: Part 3: 3.1 “Inspection”

DISCUSSION

Communications (upon closing of the poll) between the polling place and the central tabulator is expected to be provided exclusively by the landline network of the telephone service provider connected to the facility housing the polling place. The use of cell phone communications is specifically prohibited.

Source: New requirement



6.3.4.3 Conducted disturbances immunity

As described in the introductory paragraphs of Part 1: 6.3.4 “Electromagnetic Compatibility (EMC) immunity”, several ports of the voting system are gateways to possible electromagnetic disturbances, both inbound and outbound. This section dealing with conducted disturbances immunity addresses concerns about the power port and the communications ports (a combination of the in-house communications and communications to remote tabulating facilities).


Limitations of outbound conducted disturbances (“emissions” in EMC language) that might inject objectionable interference into the facility power distribution system or the telephone service connection are addressed in Part 1: 6.3.5 “Electromagnetic Compatibility (EMC) emission limits”.


6.3.4.3-A Power port disturbances

All electronic voting systems SHALL withstand conducted electrical disturbances that affect the power ports of the system.

Applies To: Electronic device

Test Reference: Part 3: 5.1.1.2-A

DISCUSSION

The power distribution system of the polling place can be expected to be affected by several types of disturbances, ranging from very brief surges (microseconds) to longer durations (milliseconds) and ultimately the possibility of a long-term outage. These are addressed in the following requirements: A.1, A.2, A.3, and A.4.

NOTE: There are several scenarios of accidental conditions that can produce voltages far in excess of the deviations implied by [ANSI06] or [ITIC00], such as loss of a neutral conductor, commingling of distribution systems with low-voltage conductors (knocked down poles, falling tree limbs). Such an event will produce in the building massive failures of equipment other than voting systems, and be obvious to the officials conducting the polling. Hardware failure of the voting system can be expected. Fortunately, the occurrence of such events is quite rare, albeit not impossible, so that such a extreme stress should not be included in the EMC requirements nor in the regimen of national certification testing – provided that the failure mode would not result in a safety hazard.

Source: [ANSI06], [IEEE02a], [ITIC00]


6.3.4.3-A.1 Combination Wave

All electronic voting systems SHALL be able to withstand, without disruption of normal operation or loss of data, a “Combination Wave” surge of 6 kV 1.2/50 µs, for high impedance power ports and 3 kA 8/20 µs, for low impedance power ports, between line and neutral terminals.

Applies To: Electronic device

Test Reference: Part 3: 5.1.1.2-A.1

DISCUSSION

The so-called “Combination Wave” has been accepted by industry as representative of surges that might occur in low-voltage AC power systems and be imposed on connected loads.

Source: [IEEE02a]


6.3.4.3-A.2 Ring Waves

All electronic voting systems SHALL be able to withstand, without disruption of normal operation or loss of data, a “Ring Wave” surge with a 0.5 µs rise time and a decaying oscillation at 100 kHz with a first peak voltage of 6 kV between the line and neutral terminals, and between the line and equipment grounding conductor terminals, and also 3 kV between the neutral and equipment grounding conductor terminals.

Applies To: Electronic device

Test Reference: Part 3: 5.1.1.2-A.2

DISCUSSION

This test waveform, proposed by IEEE since 1980 [IEEE80] as a “Standard Waveform,” and more recently adopted by the IEC [ISO06c] represents common disturbances on AC power lines but it was not included in previous versions of the VVSG. It originates during disturbances of power flow within the building, an occurrence more frequent than lightning surges. It is less likely than the Combination Wave to produce hardware destruction, but high levels still can produce hardware failure.

The “Power Quality” literature [Grebe96] and some standards [IEEE91] also cite “Decaying Ring Waves” or “Damped Oscillatory Waves” with lower frequencies but lesser amplitudes typically associated with the switching of power-factor correction capacitors. These can be significant for surge-protective device survival and possibly disruption of the operation of switched-mode power supplies. However, inclusion of the Combination Wave, the Ring Wave, and the Swells in these immunity criteria should be sufficient to ensure immunity against these lower frequency and lower amplitude decaying ring waves.

Source: [IEEE02a]


6.3.4.3-A.3 Electrical Fast Transient Burst

All electronic voting systems SHALL be able to withstand, without disruption of normal operation or loss of data, a burst of repetitive fast transients with a waveform of 5/50 ns, each burst lasting 15 ms, from a 2 kV source.

Applies To: Electronic device

Test Reference: Part 3: 5.1.1.2-A.3

DISCUSSION

While the fast transients involved in this immunity requirement do not propagate very far and are not expected to travel from the energy supply provider, they can be induced within a facility if cable runs are exposed to switching disturbances in other load circuits. Unlike the preceding two disturbances that are deemed to represent possibly destructive surges, the Electrical Fast Transient (EFT) Burst has been developed to demonstrate equipment immunity to these non-destructive but disruptive transients. Their repetitive profile increases the probability that a disruption might occur when the logic circuits go through a transition. It is important to recognize that this test, which does not represent the actual environment, is one of interference immunity, not a test of withstanding energy stress.

Source: [IEEE02a]


6.3.4.3-A.4 Outages, sags and swells

All electronic voting systems SHALL be able to withstand, without disruption of normal operation or loss of data, a complete loss of power lasting two hours and also a temporary overvoltage of up to 120 % of nominal system voltage lasting up to 0.5 second, and a permanent overvoltage of up to 110 % of nominal system voltage.

Applies To: Electronic device

Test Reference: Part 3: 5.1.1.2-A.4

DISCUSSION

Because the VVSG stipulates a two-hour back up, generally implemented by a floating battery pack, sag immunity is inherently ensured. However, the floating battery, unless buffered by a switch-mode power supply with inherent cut-off in case of a large swell, might not ensure inherent immunity against swells (short duration system overvoltages). The Information Technology industry has adopted a recommendation that IT equipment should be capable to operate correctly for swells reaching 120 % of the nominal system voltage with duration ranging from 3 ms to 0.5 s and permanent overvoltages up to 110 % of nominal system voltage.

Source: [ITIC00]


6.3.4.3-B Communications (telephone) port disturbances

All electronic voting systems SHALL withstand conducted electrical disturbances that affect the telephone ports of the system.

Applies To: Electronic device

Test Reference: Part 3: 5.1.1.2-B

DISCUSSION

Voting equipment, by being connected to the outside service provider via premises wiring, can be exposed to a variety of electromagnetic disturbances. These have been classified as lightning-induced, power-fault induced, power contact, Electrical Fast Transient (EFT), and presence of steady-state induced voltage. Within a complex voting system installed in a polling place, there is also a possibility that the various pieces of equipment can be exposed to emissions from other piece of connected equipment. In the context of the VVSG compatibility, not only must the voting system equipment be immune to these disturbances, but also the public switched telephone network must be protected against harm originating from customer premises equipment, in this context the voting system equipment. Protection of the network is discussed in the Part 1: 6.3.5 “Electromagnetic Compatibility (EMC) emission limits”. Immunity to disturbances impinging on the voting system telephone port is addressed in the following requirements: B.1, B.2, B.3, B.4, B.5, and B.6.

Source: [Telcordia06]


6.3.4.3-B.1 Emissions from other connected equipment

All elements of an electronic voting system SHALL be able to withstand the conducted emissions generated by other elements of the voting system.

Applies To: Electronic device

Test Reference: Part 3: 5.1.1.2-B.1

DISCUSSION

This requirement is an issue of inherent compatibility among the diverse elements of a voting system, not compatibility with the polling place environment or subscriber equipment other than those making up the voting system. It is understood and implemented that security requirements dictate that the voting system outgoing communications be provided by a dedicated landline telephone service excluding other subscriber terminal equipment otherwise used by entities occupying the facility when telephone communication with central tabulators is established.

Source: [Telcordia06], [ANSI02]


6.3.4.3-B.2 Lightning-induced disturbances

All electronic voting systems SHALL be able to withstand, without disruption of normal operation or loss of data, the stresses induced into the telephone network by lightning events, which can propagate to the telephone port of the voting system. The necessary immunity level is 1 kV for high-impedance ports and 100 A for low-impedance ports, both with a 10/1000 µs waveshape.

Applies To: Electronic device

Test Reference: Part 3: 5.1.1.2-B.2

DISCUSSION

Lightning events (direct flashes to the network or voltages induced in the network by nearby flashes to earth) can be at the origin of voltage surges or current surges impinging upon the interface of the premises wiring with the landline network. The provision of surge protection in the Network Interface Device (primary protection NID) is not universally provided, especially in dense urban locations, therefore the immunity level of the telephone port should be demonstrated as required by the Telcordia Generic Requirements.

Source: [Telcordia06]


6.3.4.3-B.3 Power fault-induced disturbances

All electronic voting systems SHALL be able to withstand, without disruption of normal operation or loss of data, the stresses induced into the network by power faults occurring in adjacent power distribution systems. The necessary immunity level is 600 V at 1 A for a 1 s application.

Applies To: Electronic device

Test Reference: Part 3: 5.1.1.2-B.3

DISCUSSION

For overhead telephone landline cables that share the pole with power distribution cables (medium-voltage as well as low-voltage), as well as direct burial of adjacent telephone and power cables, large power system faults can induce significant voltages and the resulting currents in the telephone network.

Source: [Telcordia06]


6.3.4.3-B.4 Power contact disturbances

All electronic voting systems SHALL be able to withstand, without disruption of normal operation or loss of data, the stresses appearing at the telephone port as a result from an accidental contact between the telephone network cables and nearby power distribution cables. The necessary immunity level between ground and the T/R conductors at 60 Hz is 600 V for short durations and 277 V for indefinite durations.

Applies To: Electronic device

Test Reference: Part 3: 5.1.1.2-B.4

DISCUSSION

Outside of the polling place building, accidental contact between the telephone network cables and power distribution cables (sharing poles for overhead, or sharing trenches for underground) can inject substantial 60 Hz current and voltages into the telephone network. Within the polling place facility, while not at high probability, instances have been noted whereby contractors working in a facility can provoke a similar injection of 60 Hz current or voltage into the premises telephone wiring. The 600 V level cited in the above requirement is associated with an accidental contact with primary power lines, promptly cleared by the power system protection, while the 277 V level is associated with an accidental contact with low-voltage distribution system that might not be cleared by the power system protection.

Source: [Telcordia06]


6.3.4.3-B.5 Electrical Fast Transient (EFT)

All electronic voting systems SHALL be able to withstand, without disruption of normal operation or loss of data, the disturbances associated with an EFT burst of 5/50 ns pulses, each burst lasting 15 ms, from a 0.25 kV source.

Applies To: Electronic device

Test Reference: Part 3: 5.1.1.2-B.5

DISCUSSION

Electrical Fast Transient bursts emulate the interference associated with electromagnetic coupling between the premises wiring of the telephone service and the premises wiring of the power distribution system in which switching surges can occur. Because these switching surges are random events, the occurrence of interference varies with the timing of their occurrence with respect to the transitions of the circuits. It is important to recognize that this requirement deals with interference immunity, not with withstanding energy stress. Immunity against such high-frequency coupling has been added to the requirements listed by [Telcordia06], effective January 1, 2008.

Source: [Telcordia06], [ISO04b]


6.3.4.3-B.6 Steady-state induced voltage

All electronic voting systems SHALL be able to withstand, without disruption of normal operation or loss of data, the disturbances associated with steady-state induced voltages and currents. The necessary immunity level is ≥126 dBrn (50 V).

Applies To: Electronic device

Test Reference: Part 3: 5.1.1.2-B.6

DISCUSSION

Voting systems interfacing with the telephone service provider plant can be subject to the interfering effects of steady-state voltages induced from nearby power lines. Through electromagnetic coupling, normal operating currents on these power lines can induce common-mode (longitudinal) voltages and currents in the outside cable plant. The 60 Hz and 180 Hz components of the induced voltage spectrum can interfere with signaling and supervisory functions for data transmission from a polling place toward a central tabulator. Higher frequencies can produce audible noise in voice-band transmission.

Source: [Telcordia06]


6.3.4.3-C Interaction between power port and telephone port

All electronic voting systems connected to both a power supply and a landline telephone system SHALL withstand the potential difference caused by the flow of surge current in the facility grounding network.

Applies To: Electronic device

Test Reference: Part 3: 5.1.1.2-C

DISCUSSION

A voting system that is powered via its power port to the power distribution system of the facility and to the telephone service provider via its telephone port can experience a potentially damaging stress between the two ports during the expected operation of the telephone network interface device in the event of a surge occurring in the telephone system. Because the level of potential differences during a surge event is principally the result of the local configuration of the premises wiring and grounding systems, and thus beyond the control of the local polling entity, inherent immunity of the voting system can be achieved by incorporating a surge reference equalizer that provides the necessary bonding between the input power port and telephone port during a surge event.

Source: [IEEE02], [IEEE05]



6.3.4.4 Radiated disturbances immunity

This section discusses radiated disturbances impacting the enclosure port of the voting system, including electromagnetic fields originating from adjacent or distant sources, as well as a particular radiation associated with electrostatic discharge.

Emissions limits requirements of radiated (and conducted) disturbances are addressed in Part 1: 6.3.5.2 ‘Radiated emissions”.


6.3.4.4-A Electromagnetic field immunity (80 MHz to 6.0 GHz)

All electronic voting systems SHALL withstand, without disruption of normal operation or loss of data, exposure to radiated electromagnetic fields of ≥10 V/m over the entire frequency range of 80 MHz to 6.0 GHz, and ≥30 V/m within frequency bands commonly used by portable transmitters.

Applies To: Electronic device

Test Reference: Part 3: 5.1.1.3-A

DISCUSSION

The proliferation of portable transmitters (cellular telephones and personal communications systems) used by the general population and the common communications transmitters used by security, public safety, amateur radio, and other services increases the likelihood that the voting equipment covered in the VVSG will be exposed to the radiated electromagnetic fields from these devices. Also, other wireless devices (wireless local area networks, etc.), communications and broadcast transmitters may be operating in the vicinity and need to be considered. Since it may be impractical to eliminate nearby radio-frequency sources, voting systems must demonstrate immunity to these signals in order to operate to a high standard of reliability. This requirement is intended to ensure intrinsic immunity to the electromagnetic environment.

Source: [ANSI97], [ISO06a], [ISO06d]


6.3.4.4-B Electromagnetic field immunity (150 kHz to 80 MHz)

All electronic voting systems SHALL withstand, without disruption of normal operation or loss of data, exposure to radio-frequency energy induced on cables in the frequency range of 150 kHz to 80 MHz at a 10 V level.

Applies To: Electronic device

Test Reference: Part 3: 5.1.1.3-B

DISCUSSION

The dominant coupling mechanism of radiated electromagnetic fields to equipment electronics at frequencies below 80 MHz is considered to be through currents induced on interconnecting cables. At these frequencies, the wavelengths are such that typical circuit components are electrically very small and thus inefficient in coupling energy directly from the radiated electromagnetic fields. The interconnecting cables, on the other hand, tend to be on the order of the signal wavelengths and may act as efficient and possibly resonant antennas. Thus, the radiated electromagnetic fields will efficiently induce currents on these cables that are connected directly to the equipment electronics.

Source: [ANSI97], [ISO06b]


6.3.4.4-C Electrostatic discharge immunity

All electronic voting systems SHALL withstand, without disruption of normal operation or loss of data, electrostatic discharges associated with human contact and contact with mobile equipment (service carts, wheelchairs, etc.).

Applies To: Electronic device

Test Reference: Part 3: 5.1.1.3-C

DISCUSSION

Electrostatic discharge events can originate from direct contact between an “intruder” (person or object) charged at a potential different from that of the units of the voting system, or from an approaching person about to touch the equipment – an “air discharge.” The resulting discharge current can induce disturbances in the circuits of the equipment.

Note: The immunity addressed in this section is concerned with normal operations and procedures at the polling place. It does not include immunity to electrostatic discharges that might occur when service personnel open the enclosure and handle internal components.

Source: [ANSI93], [ISO01]



6.3.5 Electromagnetic Compatibility (EMC) emission limits

“Emission limits” are the companion of “Immunity Requirements” – both are necessary to achieve electromagnetic compatibility. In contrast with immunity requirements that are expressed as withstand levels for the equipment, emission limits requirements are expressed as compliance with consensus-derived limits on the parameters of the disturbances injected in the electromagnetic environment by the operation of the voting system.



6.3.5.1 Conducted emissions

Electronic voting systems, by their nature, can generate currents or voltages that will exit via their connecting cables to the power supply or to the telephone service provider of the voting facility. To ensure compatibility, industry standards or mandatory regulations have been developed to define maximum levels of such emissions.


6.3.5.1-A Power port connection to the facility power supply

All electronic voting systems installed in a polling place SHALL comply with emission limits affecting the power supply connection to the energy service provider according to Federal Regulations [FCC07].

Applies To: Electronic device

Test Reference: Part 3: 5.1.2.1 “Conducted emissions limits”

DISCUSSION

The normal operation of an electronic system can produce disturbances that will travel upstream an affect the power supply system of the polling place, creating a potential deviation from the expected electromagnetic compatibility of the system. The issue is whether these actual disturbances (after possible mitigation means incorporated in the equipment) reach a significant level to exceed stipulated limits, which include the following categories:

1. Harmonic emissions associated with the load current drawn by the voting system. However, given the low values of the current drawn by the voting system, these emissions do not represent a significant issue, as explained in [IEEE92]. They are only mentioned here for the sake of completeness in reciting the range of disturbances and therefore do not require testing.
2. High-frequency conducted emissions (distinct from the harmonic spectrum) into the power cord by coupling from high-frequency switching or data transmission inherent to the system operation. These are addressed in the mandatory certification requirements of [FCC07], Class B.

Source: [IEEE92], [FCC07]


6.3.5.1-B Telephone port connection to the public network

All electronic voting systems installed in a polling place SHALL comply with emission limits stipulated by the industry-recognized organizations of telephone service providers Telcordia [Telcordia06] and TIA [ANSI02].

Applies To: Electronic device

Test Reference: Part 3: 5.1.2.1-A

DISCUSSION

Regulatory emission limits requirements for protecting the network (public switched telephone network) from harm via customer premises equipment are contained in the source documents [Telcordia06], [ANSI02], [FCC07a] and compliance to these documents is considered mandatory for offering the equipment on the market.

Source: [Telcordia06], [ANSI02], [FCC07a]


6.3.5.1-C Leakage via grounding port

All electronic voting systems installed in a polling place SHALL comply with limits of leakage currents effectively established by the trip threshold of all listed Ground Fault Current Interrupters (GFCI), if any, installed in the branch circuit supplying the voting system.

Applies To: Electronic device

Test Reference: Part 3: 5.1.3.2-A

DISCUSSION

Excessive leakage current is objectionable for two reasons:

1. For a branch circuit or wall receptacle that could be provided with a GFCI (depending upon the wiring practice applied at the particular polling place), leakage current above the GFCI built-in trip point would cause the GFCI to trip and therefore disable the operation of the system.
2. Should the power cord lose the connection to the equipment grounding conductor of the receptacle, a personnel hazard would occur. (Note the prohibition of “cheater” adapters in the discussion of general requirements for the polling place.)

This requirement is related to safety considerations as discussed in Part 1: 3.2.8.2 “Safety” – in particular the requirement to have the voting system comply with [UL05].

Note: According to [NFPA05], a bond between the equipment grounding conductor and the neutral conductor is prohibited downstream from the entrance service panel. GFCIs are designed to trip if such a prohibited bond is detected by the GFCI.

Source: [UL06], [NFPA05]



6.3.5.2 Radiated emissions

6.3.5.2-A Radiated radio frequency emissions

All electronic voting systems installed in a polling place SHALL comply with emission limits according to the Rules and Regulations of the Federal Communications Commission, Part 15, Class B [FCC07] for radiated radio-frequency emissions.

Applies To: Electronic device

Test Reference: Part 3: 5.1.2.2-A

DISCUSSION

Electronic equipment in general and modern high-speed digital electronic circuits in particular have the potential to produce unintentional radiated and conducted radio-frequency emissions over wide frequency ranges. These unintentional signals can interfere with the normal operation of other equipment, especially radio receivers, in close proximity. The requirements of [FCC07] and [ANSI06a] are intended to minimize this possible interference and control the level of unwanted radio-frequency signals in the environment.

Source: [FCC07]



6.3.6 Other requirements

In addition to the requirements associated with EMC discussed in the preceding sections, there are other requirements, including dielectric withstand, personnel safety considerations (addressed in Part 1: 3.2.8.2 “Safety”) and hardware failure modes (which can also be a safety issue) [UL05].



6.3.6.1 Dielectric withstand

6.3.6.1-A Dielectric stresses

All electronic voting systems SHALL be able to withstand the dielectric test stresses associated with connection to the network, characterized by limits of the admissible leakage current.

Applies To: Electronic device

Test Reference: Part 3:5.1.3.1-A

DISCUSSION

Dielectric withstand requirements stipulated by industry-consensus telephone requirements as a condition for connecting equipment to their network involve the insulation and leakage current limits between elements of the voting system hardware, including the following:

1. Network and device or accessible circuitry which might in turn connect to the user;
2. Network and hazardous power system; and
3. Power equipment.

Source: [Telcordia06]



6.4 Workmanship

This se