As well as the inadequate operating performance she said there was "an increasingly competitive global capacitor market and ageing manufacturing equipment and processes".
"It is no longer sustainable for Ampcontrol to maintain its manufacturing facility for capacitor products in Rotorua," she said.
The company will use its Melbourne plant to meet the needs of the New Zealand market.
The closure is being staggered but the doors have already closed. The firm will continue to work with its New Zealand customers and will stand by warranty commitments, she said.
The Rotorua firm was formerly known as Metalect. It has been in Rotorua for 27 years and was bought eight years ago by Ampcontrol. It was the only company in Australasia that made medium-voltage capacitors.