The maximum number of VVPAT machines which faced glitches were changed in the South Delhi Lok Sabha constituency while the minimum were replaced in the Northeast segment which delayed the poll process on Sunday, EC officials said.

An Electronic Voting Machine (EVM) comprises of three parts – the Control Unit (CU), the Ballot Unit (BU) and the Voter Verified Paper Audit Trail (VVPAT) machine.

Officials said the VVPAT machines are extremely sensitive to light and heat and being a new technology, glitches arose which delayed voting at some places.

At the Nirman Bhawan polling booth, where several VVIPs including Vice President Venkaiah Naidu cast their votes, technical snags in the EVM arose thrice before it was changed.

Officials said there was a connection error between the EVM’s BU and CU.

Sources in the poll panel said the problem with the EVM first arose at 7.30 am, then at 9.30 am and again at 10.30 am which delayed voting.

The Election Commission officials said that overall, 61 BUs, 35 CUs and 286 VVPAT machines were changed in the national capital due till 3 pm due to technical snags.

In the Chandni Chowk parliamentary segment, 21 VVPATs, 2 BUs and a CU were changed, while in East Delhi, 81 VVPATs, 10 BUs, 6 CUs were replaced.

In Northeast Delhi, 3 VVPATs, 2 BUs and a CU were replaced while in the New Delhi constituency, 28 VVPATs, 12 BUs and 6 CUs were changed.

Similarly, in the Northwest segment, 72 VVPATs, 9 BUs and an equal number of CUs were changed, while in West Delhi, 18 VVPATs, 12 BUs and 6 CUs were replaced. In South Delhi, 87 VVPATs, 18 BUs and 8 CUs were replaced.

According to Chief Electoral Officer, Delhi, Ranbir Singh, mock polls were held in the morning and defective machines were replaced.

A total of 5.5 per cent of the EVMs were replaced in the morning and that might have caused delay in start of the polling process, he said.