NR NB 162 ISSUE 1 PDF

This instruction applies where an LED signal has TPWS Method 3 proving or where a filament head is replaced by an LED head having Method 3. It can also be applied to filament signals where the aspect reversion condition is exhibited.

Purpose of NB

This Notice Board describes:

i) the alteration to remove the short-duration aspect reversion which occurs on signals reading towards an LED signal that is fitted with TPWS Method 3 proving;

ii) a solution to overcome the ‘aspect blinking’ of LED banners which are lamp proved with pc569 relays.

These modifications have been designed as a Functionally Equivalent (FED) replacement of the relay and its base. When embodied into the relevant NR documentation, this NB will be withdrawn.