"In all 21 VVPAT machines of 212 placed in 10 constituencies in Aizawl district failed.
Eleven VVPATs failed during routine checkup a day before the assembly polls, 10 more were unsuccessful during the polling day and had to be replaced," Mizoram Chief Electoral officer (CEO) Ashwini Kumar told reporters.
He said that the Electronic Corporation of India Ltd (ECIL) delivered the machines to the Mizoram election department two weeks late which, coupled with the breakdown of the devices, led to "administrative challenges".
"The VVPAT is a printer with a drop box attached to EVMs (Electronic Voting Machines), which permits voters to confirm their vote was cast in the way they desired," Kumar said.
He said: "As soon as the voter casts the vote, the VVPAT would show a tiny slip in a glass covered display with the symbol and the candidate name the elector has voted for. The slip after 3 to 4 seconds would automatically drop down into the connected closed box."
A Mizoram election department official said that following several court cases against the EVMs and some controversy over the electronic machine, the VVPAT is being used to satisfy the voters and to remove doubts about the voting machine.
The VVPAT devices were used for the first time in the Noksen by-polls in a Nagaland assembly segment in September and then in 10 of Mizoram's 40 assembly constituencies.
The VVPAT, which was developed by the Hyderabad-based ECIL under the Department of Atomic Energy, are scheduled to be used in select constituencies of the Dec 4 Delhi assembly polls.
An Election Commission of India official said in New Delhi that ECIL engineers had been summoned Dec 3 in view of the malfunctions.