scope:

Introduction

The standard range of miniature relays is commonly known as the BR 930 series. They have plugboard bases which can be configured so that only relays of the type intended can be fitted.

The relay unit is configured by a number of pins protruding from it. Each type of relay has a different pattern of pins. The plugboard bases have corresponding holes. The patterns are chosen so that it is impossible to plug an unsafe type of relay into a particular base.

Figure 1 shows the view of a plugboard base from the relay side. There are at least 13 hole positions. Each hole position used for relay or Reed plugboards has a letter code as shown.

Bases drawn from general stock have no configuration holes drilled in them. The hole positions are marked by dimples which act as drilling guides.