Thanks Mal, I did not realise it was that early. I seem to recall that they had some teething troubles with overheating components but sorted that out. The joy of commissioning a new design.

To answer another of Mick’s questions DC electronic drives, regardless of the technology used, eliminate the need for any form of transition steps. The motors are usually permanently connected in parallel.

Geoff O.

From:tramsdownunder@... [mailto:tramsdownunder@googlegroups.com] On Behalf Of Mal Rowe
Sent: Monday, 18 March 2024 11:24 AM
To:tramsdownunder@...
Subject: Re: [TramsDownUnder] "Chopper Controls"

On 17/03/2024 20:13, 'Geoff Olsen' via TramsDownUnder wrote:

Regarding the above when did the first Thyristor drive Zs go into service?

The Z3s were the first to be fitted with chopper controls and regenerative braking as standard with Z3 entering service on 25 Sep 1979.

A first day pic by David Featherstone is in the TDU archive at: https://tdu.to/i/69473

Prior to that Z1 No 5 was fitted with chopper control and regenerative braking for testing purposes in November 1977.

5 was returned to the normal Z1/Z2 control system in 1983 using equipment salvaged from 102 which was destroyed by fire.

Mal Rowe who saw '102' on some of the equipment on No 5 at Bylands.