The EC had formed two special teams to look into the unusually high number of voter verifiable paper audit trail (VVPAT) machines malfunctioning in Uttar Pradesh's Kairana and Maharashtra's Bhandara-Gondiya on May 28.
The preliminary report found two major technical reasons for the malfunctioning -- failure of contrast sensor and failure of the length sensor.
"These errors are mainly caused by excessive exposure to illumination in the polling stations," the EC said, citing the preliminary report submitted by the probing teams.
"The commission has asked the manufacturers and the technical expert committee (TEC) 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 poll panel said.
"The commission has also adopted the hardware improvement recommended by the TEC to prevent auto shut down of VVPATs due to excessive light," it added.
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