SON High Pressure Sodium

Updated
25-X-2021
The High Pressure Sodium lamp is the invention of General Electric USA, although Osram-GEC and Associated Electrical Industries of Britain were also key players in the race to be first to create this lamp. The fundamental principle behind the lamp is that the narrow, monochromatic sodium resonance lines can be considerably broadened if the sodium vapour pressure is increased. However, higher wall temperatures are required to achieve this and the advanced glasses which can just about withstand sodium attack in the low pressure lamp become blackened in a matter of minutes at higher temperature.

The key to the success of the high pressure sodium lamp is an arc tube fabricated of translucent ceramic, since there is no known glass which withstands the corrosion of sodium at high temperature. Aluminium oxide (alumina) is the chosen ceramic since, when combined with minute traces of dopants to control the grain structure, it can be made translucent by a process which is suited to mass production.

Once the ceramic tube is made, the problem of sealing an electrical conductor through it must then be faced. It is standard practice to use special sealing glasses, but these still represent a weak point in the lamp design. Other designs are liable to cracking or may leak over time. The lamps on this page highlight many of the different sealing techniques which have been tried, while also representing a broad selection of the different lamp styles that have been made available over the years.

Standard Lamps

GE

500W
Early Prototype of First Lucalox Lamp
~1965

GE

400W
LU400/BD with external amalgam reservoir
1971

GE

1000W
LU1000/BD with auxiliary electrode
~1971

GE

250W
LU250 Universal with butterfly crimp reservoir
1983

GE

125W?
LU125/BD low power experimental lamp
~1970

GE

70W
First 70W-LV lamp, with Molybdenum heat pipe
1976

GE

50W
LU50 Early low wattage with niobium wire seals
1980

GE

70W
LU70/90/T10/27 Compact Tubular
1992

GE

1000W
LU1000 with voltage fuse in outer jacket
1980

GE Mexico

150W
LU150 55-Volt of Mexican Design
~1985

Tesla

400W
Early Czech lamp with metal end seals
1967

Atlas

250W
Early British KolorSON with metal end seals
1969

Philips

400W
SON-T 400W with monolithic ceramic seals
1971

Westinghouse

150W
C150S56 Canadian lamp with niobium cup seals
1974

Tungsram

400W
TC 400 with unusual large end seals
c. 1975

Thorn

70W
First 70W-HV lamp, with wide bore arc tube
1976

Thorn

70W
Early low wattage lamp with large bore arc tube
1983

Thorn

50W
Early low wattage lamp with large bore arc tube
1987

Polamp

400W
WLS 400 with early Niobium cup seals
1978

Philips

250W
SON-T with scraped-tip electrode assembly
1980

Norleco

250W
SON-T of Philips American design
1980

Sylvania

200W
Lumalux LU200 of unusual power rating
1982

Thorn

400W
SON-T with prototype Cermet arc tube seal
1983

Tungsram

250W
TC 250W with double niobium wire seals
1985

PZGRL

400W
DNaT 400-4 of early Ukranian design
1985

Tesla

70W
SHC with Monolithic 2-Piece PCA design
1987

Thorn

1000W
SON-T 1000W with narrow bore Nb seals
1988

Thorn

70W
SON-T with cermet arc tube seals
c. 1991

Osram

70W
SON-Plus with side arm to measure vacuum
1991
   

Diffuse Outer Bulb

Philips

400W
SON-E 400W with diffuse outer envelope
1971

Atlas

400W
KolorSON 400W with diffuse outer envelope
1974

Thorn

40W
SON-E Experimental low wattage lamp
~1983

GE-Thorn

50W
SON-E with pearl glass outer envelope
1992

Philips

250W
Tubular SON with Coated Outer Bulb
~1985

GE

50W
LU50/90/D/27 with diffuse outer envelope
1987

Osram

70W
NAV-E 70W/NB low voltage for Leipzig City
1993
       

Transparent Arc Tube

GE

100W
Flux polished polycrystalline arc tube
1976

Westinghouse

400W
Corstar single crystal sapphire arc tube
1977

Thorn

400W
Corstar single crystal sapphire arc tube
1981

Thorn

70W
Corstar single crystal sapphire arc tube
~1983
       

Instant-Restrike Twin Arc Designs

Sylvania

400W
SHP-Standby twin arc tubes for hot restrike
1989
       

Self-Starting & Mercury Retrofit Designs

OsramGEC

310W
Solarcolour Plug-In Mercury lamp retrofit
1969

OsramGEC

120W
SON-I with internal snap-switch starter
1976

Sylvania

360W
Unalux Penning-Start Mercury lamp retrofit
1982

GE

215W
E-Z Lux Penning-Start Mercury lamp retrofit
1988

Philips

70W
SON/I with internal glowbottle starter
1980

GE

70W
LU70/90/D/I/27 internal electronic ignitor
1990

Iwasaki

150W
Ignitron NHT150-I with internal FEC ignitor
1997

Iwasaki

150W
SunluxUltra NH150CE Unsaturated Vapour
2000

Sylvania

69/108W
SPX EcoArc Unsaturated Mercury Retrofit
2009

Enhanced Efficacy Designs

GE

250W
LU250/BD/S with Superior Performance
1977

OsramGEC

310W
Solarcolour Plus early high efficacy lamp
1987

GE-Thorn

70W
SON XL-T with Cermet arc tube seals
1991

GE-Thorn

400W
SON XL-T with sintered moly antenna on tube
1991

Sylvania

100W
SHP-MF Mercury-Free high pressure sodium
1996

GE

70W
Lucalox XO with monolithic arc tube
2008

Deluxe Colour

OsramGEC

400W
Solarcolour SONDL-T Deluxe Colour
1985

Thorn

400W
SONDL-T Deluxe Colour
1988

Philips

250W
SON-T Comfort Deluxe Colour
1989

GE

400W
Lucalox LU400/DX/40 Deluxe Colour
1998

Thorn

400W
SON-Deluxe with dichroic filter sleeve
~1983
   

White Light

Matsushita

50W
K-HICA-Light White with elliptical arc tube
~1985

Iwasaki

50W
NHT50 SDX White SON High Colour Rendering
~1985

Philips

50W
SDW-T White SON with high CRI
1991

Philips

50W
SDW-R White SON Blown Reflector
Early 1980s

Philips

22W
SDW-AR White SON Crown Silver Replica
1986 + 2018

GE

95W
White Lucalox for Pulsed Operation
1990

Philips

150W
SON-T Deco for City Beatification projects
1995

Philips

100W
SDW-TG Reduced size Mini WhiteSON
2002

Osram

80W
ColorStar DSX-T with Variable Colour Output
1998

Reflector Style

Westinghouse

70W
Ceramalux C70S62/PAR Dichroic for Coal Mines
1970s

Osram

310/360W
SON-R Mercury-Retrofit high pressure sodium
1998

Thorn

70W
SON-R Reflector style high pressure sodium
1982

Reflux

250W
Reflux lamp with special side reflector
2003
       

Linear Style

Thorn

250W
SON-TD Quartzray Gas-filled Linear style
1981

Thorn

400W
SON-TD Quartzray Gas-filled Linear style
1987

Thorn

1000W
SON-TD Quartzray Gas-filled Linear style
~1990

GEC

250W
SON-L SolarStream Gas-filled Linear style
1996

Osram

400W
NAV-TS Vialox Standard Gas-filled Linear style
1989

Osram

150W
SON-TS Super double ended design
2000

COBR

400W
WLS-TC Double ended quartz prototype
~2000

Philips

1000W
Master GreenPower Horticultural Linear
2005