Industrial Drive Service Inc. is a drive systems integrator business based in Hensall, Ontario. Most of their projects involve a motor, drive and a programmable logic controller. One of their niche markets is hoist controls used in the mining industry. In 1995 they were involved with a hoist installation in Peru. The project went well and resulted in many subsequent hoist projects, the latest being in 2019.
In the early days of variable speed drives, Nema rated motor contactors were used. The more economical IEC rated contactor had not be introduced. As variable speed drive technology improved and sequencing the opening of the contactor to coordinate with the termination of current flow to the motor became reliable, the need for a contactor to break an arc took second place to the use of a contactor for isolation purposes. This meant that the more robust and more expensive Nema contactor was not required.
I recently had a situation occur where a customer had a VFD fail and asked me to set up the spare in its place.