Re: Master Clock contact spark quenching
Interesting. The Silent Electric (closely related to early GPO clocks) uses make before break and resistors (unknown, but very probably just like the GPO ones). The were designed to work with Silent Electric’s own ’Silectock’ rotary armature mechanism at 250 mA and some systems used many dials. No mention is made of relays in the contemporary literature (1919 catalogue) which states;toggle quoted messageShow quoted text
“The contact arrangement consists of two pairs of platinum points - one being for the line circuit for the dials and the other for the shunt or short circuit, according to whether the clocks are operated from battery or from electric light supply. The motion given to the contact springs in conjunction with this method of cutting out the shunt, except for the instant prior to breaking the circuit, results in sparkless action”.
The terminals in the clocks are marked “Pendulum Battery”, “Dials Battery” and “Dials”. The same contacts and markings are used in both the 1/2 second and 1 second pendulum versions of the clocks.