[GreenKeys] We Co 255 Polar Relay

[Don Mehl]

                The  use is as a repeater.  The teletype machines require a 60-milliampere neutral current to operate the printer.  Neutral means that positive current would flow for a mark or no current for a space.  A polar signal uses a positive current for a mark and a negative current for a space.  On longer wire line circuits polar operation is used.  The relays convert the signal from polar to neutral when required and also provides the 60-milliampere line current for operating the printer.  On long circuits the line current was 30-milliamperes.   Distortion and deterioration of the signal over long wire lines are removed by the relays so that the printer will operate properly.  The relays would also be used as repeaters at relay points to extend the distances beyond 40 miles.