Permus (1982 - ?)
Developed from Tempus dimmers
Permus Dimmer Racks, embodying Permus Thyristor dimmer modules, are the economic power-handling component for permanent, hard-wired lighting control systems. These shallow racks require only front access, plus top access for the electrical contractor, and can be mounted against a wall, or mounted back to back; either method ensures that only the very minimum of valuable floor space is required.
The rugged and reliable Permus dimmer modules incorporate a temperature-stable trigger card with hard firing on each pair of tungsten surge-rated Thyristors mounted on generous heat-sinks. Hard-firing ensures stable operation on loads as low as 40 watts and for transformer-fed lamps. A new transfer characteristic has been incorporated to give increased control sensitivity, and improved standards of reliability, and safety, are ensured by elimination of the bottom-set potentiometer.
The standard width Permus racks, stocked and ready for despatch, are already fitted with either 24 x 10A dimmers in twin module format, or alternatively 12 x 20/25A single dimmer modules. For maximum flexibility of the total number of dimmer channels, and to allow mixed ratings in a multiple rack installation, there is also a narrower rack available housing either 12 x 10A, or 6 x 20/25A dimmers. All Permus dimmer racks employ natural air flow ventilation, are available with either Reyrolle or Neozed close-excess current protection, and are internally wired for a three phase and neutral incoming supply. Provision is made to allow each two adjacent dimmer modules (4 x 10A) to be changed, on site, to a different phase, or to change to a single phase and neutral supply.
Tempus Control Desks
For use with Tempus desks a power supply unit needs to be added to one Permus rack and twin or quad control socket boxes are necessary to receive the plug-terminated flexible cable for each block of 6 channels.
From Rank Strand information leaflet "Preset Lighting Controls and Dimmers"
Strandbook - Permanent Dimmer Racks (1989)
Catalogue & Journal Entries for Permus in the Backstage Heritage Collection