"Excessive exposure" to illumination might have led to the malfunctioning of paper trail machines attached to EVMs in the bypolls to Kairana and Bhandara Gondiya Lok Sabha seats, the Election Commission said today.
Quoting preliminary fact-finding reports by its two teams, the commission said the failure of contrast sensors and failure of length sensor were the two major technical reasons for the malfunctioning of voter verifiable paper audit trail (VVPAT) machines during the May 28 bypolls.
"...errors are mainly caused by excessive exposure to illumination at the polling station," the EC said in a statement.
It has now asked the two manufacturers of the VVPAT machines -- Electronics Corporation of India Limited (ECIL) and Bharat Electronics Limited (BEL) -- and its technical expert committee to suggest additional design improvements as well as suggestions on any layout changes in the polling stations to prevent any excessive exposure to illumination in future.
The manufacturers will also carry out a detailed analysis of the machines once they are free from the polling process after 45 days.
Any candidate can file an election petition in a high court within 45 days and till that period is over, electronic voting machines (EVMs) and VVPATs are kept in a strong room as they can be summoned as evidence by the court.
Over 11 per cent VVPATs were replaced during the bypolls.
"Malfunction was in VVPATs. Factors responsible may include first-time use by polling staff whereas they have developed expertise in managing EVMs, extreme heat, placement of VVPAT under direct light and mishandling during use. EC conducts root cause analysis in such cases to improve (functioning) in future," an EC spokesperson had then said.
The EC said out of 10,365 VVPATs, 1,202 were replaced. It comes to 11.60 per cent.
Concerns were raised by parties about the functioning of paper trail machines including for the bypolls to Kairana Lok Sabha seat and Noorpur assembly constituency in Uttar Pradesh and Bhandara Gondiya Lok Sabha seat in Maharashtra.
An official had said those who skipped training programmes and "spent time on their phones during training sessions" placed the machines at places where "heat sensitive" nature of the device created problems.