Alex Seal

Bristol East Signal Box

Introduction

Bristol East Illuminated

Bristol East Alive! Clcik to enlarge...

A few photos

Photographers

Maurice W Earley

Collection with NRM? - APRoGWS page 72

Adrian Vaughan

APRoGWS page 41

Track Circuit Lamps

T2 - 7mm Telephone Slide Base Filament Lamps

Filament lamps will perform to specification and give optimum life when:
a) they are powered at the rated voltage from a stabilised 50 Hz A.C. supply
b) ambient temperature is in the range 20°C to 25°C
c) no mechanical vibration is present.
Deviations from these criteria can have a significant effect on lamp life, particularly with low current filaments (<80 mA).
Operation from a d.c. supply at rated voltage can reduce specified life by up to 50%.
The effect of variation from the rated operating voltage should be noted:
5% above will reduce lamp life by up to 50%.
5% below will significantly increase lamp life.
Current consumption can vary by up to ±10% on stated values at rated supply voltage. Care therefore should be exercised when running a number of lamps in series. In such applications it is recommended that the rated voltage be reduced by 10% to prevent premature failure of individual lamps.

Technical specification

Voltage 12V
Current 100mA = 0.1A
Lumens 3
MSCP 0·24
Average life (hrs) 2,000

1 ampere = 1 000 milliamperes

123 Track Circuits = 246 Lamps
246 x 0.1A = 24.6 Amps

P=IV 24.6 x 12 = 295.2Watts

Further Reading