Howard Industries HID Lamp Service Guide
HID Lamp
Service Guide
580 Eastview Drive | Laurel, MS 39443
800.956.3456
www.HowardLightingProducts.com
Page 2
High Intensity Discharge
Servicing Guide
Table of Contents
OVERVIEW .............................................................
IMPORTANCE OF SAFETY ....................................
INTRODUCTION TO HID LIGHTING ......................
HID OPERATION AND CONSTRUCTION ..............
Mercury Vapor and Metal Halide Lamp Starting …..
Ballasts ....................................................................
Arc Tube Design ......................................................
HPS End-of-Life Voltage .........................................
HID OPERATING CHARACTERISTICS..................
TABLE 1: HPS Lamp Data.......................................
HID LAMP LUMEN MAINTENANCE .......................
HPS Lamps .............................................................
Mercury Vapor Lamps .............................................
Metal Halide Lamps .................................................
HID LAMP LIFE .......................................................
HPS Lamps .............................................................
Mercury Vapor Lamps .............................................
Metal Halide Lamps .................................................
THE HPS LUMINAIRE ............................................
HPS Lamp Starters ..................................................
Starter Operation .....................................................
HID Lamp Starter Stoppers......................................
Starter Stopper Wiring Information…………………..
HID LAMP BALLASTS.............................................
Ballast Characteristics .............................................
Reactor Ballasts ......................................................
3
Lag Auto Ballasts ...................................................
3
Constant Wattage Autotransformer Ballasts ……...
4
Matching Lamp and Ballasts ..................................
5
PHOTOCONTROL OPERATION AND
6
TROUBLESHOOTING ...........................................
7
HPS LAMP CYCLING.............................................
7
Equipment Mismatching ...................................…..
8
Reignition Phenomenon .........................................
9
Vibration Sensitivity ................................................
9
Thermal Cycling .....................................................
10
Photocontrol-Induced Cycling ............................…
10
COST-EFFECTIVE SERVICING OF
10
HPS LIGHTING SYSTEMS ...................................
10
Test Procedures .....................................................
10
Selecting the Test Group .......................................
11
Visual Inspection ....................................................
11
TESTING HPS SYSTEMS IN THE FIELD .............
11
Voltmeters ..............................................................
12
SERVICING HPS LUMINAIRES AT
12
AN INSTALLED LOCATION ..................................
12
HPS Luminaire Failures .........................................
14
GLOSSARY OF ELECTRICAL
TERMS ..................................................................
16
APPENDIX A .........................................................
17
APPENDIX B .........................................................
18
APPENDIX C………………………………………….
19
19
20
20
20
22
22
23
23
24
24
25
25
25
26
26
27
27
28
30
32
34
36
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Page 3
OVERVIEW
Howard Lighting Products is pleased to present you with the
High Intensity Discharge Lamp Service Guide. The primary
focus of this guide is to give information on HID lighting systems with an emphasis on High Pressure Sodium lamp fixtures. Regardless of the manufacturer, this guide will help
you troubleshoot and solve basic problems relating to HID
lamp systems.
This service guide includes diagrams, illustrations and tables to better explain operation and servicing these lamps.
IMPORTANCE OF SAFETY
HID lamp servicing requires close attention to safety. Working with electrical equipment at significant heights can be
dangerous if proper preparations and precautions are not
taken. The following is a general safety checklist. Always
follow the exact safety procedures outlined by your company.
1. Park the lift truck at the safest possible location at the
work site. Set up safety cones to direct traffic around the
truck.
2. Before beginning, check the lift bucket of the truck to
make certain it is secure. The pivot point mounting should
be tight with no cracks or breaks. Also make certain the
bucket is equipped with a fiberglass liner and that the liner
is in good shape with no cracks or breaks. Although not a
common problem, lamps have been known to shatter due to
operational problems or when being turned into or out of the
socket.
3. Make sure the boom strap is in place and secure.
4. Make certain the lanyard is in good shape, fastened and
secure. The safety belt also must be in good condition.
5. Always strap on the safety belt before raising the bucket.
Putting the safety belt on should be the first thing you do
after stepping into the bucket.
6. Always use a properly secured safety belt when working
from ladders.
7. Always wear a hard hat when servicing a luminaire in the
field.
8. Wear work boots with non-slip insulating soles.
9. Always wear high-voltage gloves when servicing and
replacing luminaires. Inspect the gloves at the start of each
workday for holes and tears. Replace damaged gloves immediately. Keep your high-voltage gloves in the glove bag
Topics include:
• Basic notes on lamps.
• Basic construction and operation of HID lamps.
• Unique construction and operating features affecting ser-
vicing. Special attention is paid to starting circuits, ballasts
and photocontrols.
• An in-depth look at the causes of the cycling ON and OFF
of the HPS lamp, including end-of-life cycling.
• Test equipment for servicing HPS lamps and luminaires,
including the drawbacks of voltmeters.
• Troubleshooting the HPS luminaire in the field.
• Factors to consider and problems associated with the in-
stallation and use of mercury vapor to HPS conversion kits.
located in the bucket so they will always be available when
needed.
10. Always wear proper eye protection whenever you work
on luminaires or replace a lamp. Although not a common
problem, lamps have been known to shatter due to operational problems or when being turned into or out of the
socket.
11. Luminaires can be heavy. Position the bucket so you do
not have to overreach or stretch while lifting or handling the
luminaire. Always secure the luminaire, cover and any other
items or tools inside the bucket so there is no danger of
them falling to the ground.
12. Always be certain the luminaire is properly grounded.
Use the grounding screw provided and run back to mechanical ground. If the luminaire is not properly grounded, it
may become electrically ―hot‖ if a component or wire inside
the housing grounds itself to the housing. This can happen
if wires become frayed, or ballasts or other components are
damaged. The danger of electrical shock then exists when
the service technician touches the housing and grounds
another part of his or her body. The feeling of static electricity when you are near to, or brush lightly against a luminaire
is a sign that it may be electrically ―hot.‖ De-energize the
fixture immediately and inspect for a possible short to
ground inside the housing.
13. If a lamp (light bulb) should break during installation or
removal, de-energize the fixture and remove the broken
lamp from the socket using a broken lamp base extractor.
14. Work carefully and use good judgment in all situations.
Most accidents are the result of carelessness.
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Page 4
INTRODUCTION TO HID LIGHTING
High Intensity Discharge (HID) lighting includes high pressure sodium, metal halide and mercury vapor lamp
groups. The HID lamp group is by far the most important lamp group used in modern exterior and industrial lighting. HID light sources are highly regarded for their long life and high efficacy. The compactness of HID lamps
also increases optical control and allows for a great deal of adaptability in the area of luminaire design.
HID systems are the most cost-effective method of lighting roadways, parking areas, sports fields, signs and
buildings. HID systems also are ideally suited for interior applications such as sports arenas, warehouses, industrial plants and certain types of indirect office and commercial lighting.
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HID OPERATION AND CONSTRUCTION
All HID lamps share a number of design and operating features, but there are some important differences between mercury vapor, metal halide and HPS lamps (Figure 1). All HID lamps contain a sealed arc tube mounted
inside a glass bulb. In mercury vapor and metal halide lamps, the bulb is filled with hydrogen gas, which absorbs
the ultraviolet radiation produced during operation. HPS lamps have a vacuum inside the bulb to isolate the arc
tube from changes in ambient temperature. As the arc tube is manufactured, small amounts of special arc metals, such as mercury, halide compounds or sodium, are sealed inside the tube. Starting gases, such as argon,
neon or xenon, are placed inside the tube. The arc tube also houses the lamp’s two main electrodes, plus the
separate starting electrode used in mercury vapor and metal halide lamps. An HID lamp produces light in much
the same manner as a lightning bolt. But instead of a brief flash, the electric arc between the lamp’s two main
electrodes is continuous. The striking and maintaining of this continuous arc is made possible by the starting
gases and arc metals sealed inside the arc tube. The proper start-up voltage also is needed to establish the arc.
Lamp start-up is not the same for all HID lamps.
Figure1. Components of HID lamp designs.
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Page 6
Mercury Vapor and Metal Halide
Lamp Starting
Both mercury vapor and halide lamps use a separate
starting electrode. This starting electrode is located next
to one of the main electrodes inside the arc tube. The
start-up electrode allows these lamps to be started using a much lower start-up voltage than required by HPS
lamps.
When a mercury vapor or metal halide lamp is energized, an electrical field is generated between one of
the main electrodes and the starting electrode next to it.
This causes an emission of electrons that ionize the
argon starting gas. The ionized argon particles create a
diffused argon arc between the two main electrodes of
the lamp (Figure 2).
The heat from this argon arc gradually vaporizes the arc
metals in the arc tube. These ionized arc metal particles
join the arc stream between the two main electrodes.
When a sufficient number of ionized particles join the
arc stream, the resistance between the main electrodes
drops to a point where the start-up voltage supplied by
the ballast can strike a current arc across the main electrodes. The arc current continues to increase until the
current rating of the lamp is reached; a process that
normally takes several minutes.
The HID arc consists of a very rapid flow of both electrons and charged arc metal ions. During this rapid
movement, countless collisions occur between ions and
electrons. As these particles collide, they release energy at a specific wavelength (Figure 3). This energy
appears to us as light. Because the number of particles
in the arc tube is so great and the occurrence of collisions so frequent, it appears that the entire arc path
constantly generates light.
The color of the light is a characteristic of the light spectrum wavelength of the arc metals contained in the arc
tube. For example, in a mercury vapor lamp, the mercury produces a distinct greenish white-blue light. Red,
orange and yellow hues appear grayish.
Figure2. Mercury vapor or metal halide
lamp starting using a starting electrode.
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Figure3. Light production in an HID lamp.
Page 7
Figure4. Components of HID lamp designs.
In a metal halide lamp, the arc discharges through the combined vapors of mercury and certain compounds of
iodine. The halide compounds help strengthen yellows, greens and blues, so the overall color rendering of metal
halide lamps is green-white. Reds and oranges appear dulled. Phosphor coatings on the bulbs of mercury vapor
and metal halide lamps can improve color rendering and provide light diffusion.
Once a mercury vapor or metal halide lamp starts, voltage drops to lower operating voltage levels. A resistor or
thermal switch in series with the starting electrode now blocks voltage to the starting electrode so it does not arc
and burn out during normal lamp operation.
The arc tube of an HPS lamp is too narrow to house a separate starting electrode. Since there is no starting
electrode in an HPS lamp, a much higher start-up voltage is required to establish an arc between the wide gaps
of the main electrodes. This low-power, high voltage spike ranges between 2500 and 4000 volts. This voltage
spike or pulse is provided by a starter pulse circuit board separate from the ballast (Figure 4).
Note: Some lower wattage metal halide lamps (70-, 100- and 150-watt) also have arc tubes that are too
narrow to house separate starting electrodes. These metal halide lamps now use an external starter
board such as those used in HPS lamps.
When an HPS lamp is energized, the high-voltage pulse ionizes the xenon gas in the arc tube, and an arc is established between the main electrodes. As soon as this arc is established, the voltage pulse is switched off. Sodium and mercury arc metals quickly vaporize and join this arc stream, and the arc current increases and stabilizes.
HPS lamps generate a sodium-based light that is strongest in the yellow and orange range of the spectrum and
weakest in the blue-green wavelengths. A small amount of mercury is added to the arc tube to help strengthen
blues and greens, but the overall color rendering is still golden white, with both reds and blues appearing grayed.
Ballasts
All three types of HID lamps require the use of a ballast to assist in starting and limiting the current across the
arc once the arc has been struck. Remember that HID lamps are negative resistance lamps. If a ballast were
not used, the arc discharge would draw an unlimited amount of current and the lamp quickly would be destroyed.
More complete ballast information can be found later in this manual.
Arc Tube Design
The arc tube of mercury vapor and metal halide lamps is shorter and wider in diameter than an HPS arc tube.
This allows room for the starting electrode. Mercury vapor and metal halide arc tubes are thin-walled tubes made
of high-quality quartz. The ends of the tube are sealed by flame forming. This one-piece, press-fit construction
assures greater uniformity between lamps and also holds and protects the thin leads of the electrodes. As the
two ends of the arc tube are heated and pressed together, the two main electrodes and thinner, starting electrode are imbedded in the molten glass. The arc metal and starting gas are fed into the tube through a glass
straw welded into the arc tube. As the glass straw is heated to the melting point, the opening seals, trapping the
gas and arc metal inside.
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Both mercury vapor and metal halide arc tubes are filled with the exact amount of arc metal (commonly called
amalgam) needed for operation. After an initial 100-hour burn-in time by the end user, mercury vapor and metal
halide lamps reach a stabilized operating point at which all arc metal inside the tube is ionized during start-up
and operation. At this point, lamp voltage becomes relatively constant throughout the rest of the lamp’s operating
life. There is a very slight voltage rise, but it is not great enough to affect the life span of the lamp. The same is
not true of HPS lamps.
The arc tube of an HPS lamp is a slender cylinder approximately 1/4‖ to 3/8‖ in diameter. Sodium cannot be con-
tained in a glass tube. The sodium would etch the glass and further degrade light output. Sodium must be contained in a metal container. Most lamp manufacturers use a special ceramic material known as polycrystalline
alumina (PCA) to construct the HPS arc tube. PCA is basically an aluminum oxide material virtually insensitive to
sodium attack.
PCA tube materials do not lend themselves to the molten sealing method used in the construction of mercury
vapor and metal halide arc tubes. Instead, PCA end caps, using either a wire-out end seal or a compound
(shrink-fit and cemented) end seal, are epoxied or glued to the tube body using silicone glass Each tube end cap
contains an electrode. The sodium-mercury amalgam and starting gases are placed inside the arc tube before it
is sealed closed.
Unlike mercury vapor and metal halide lamps, HPS lamps are excess amalgam lamps. This means there is
more sodium and mercury arc metal placed inside the tube than can be vaporized during start-up and operation.
The amount of amalgam that vaporizes depends on the total energy in the arc and the temperature of the amalgam. If the lamp becomes too hot, too much amalgam will vaporize, and operating voltage will increase.
When HPS lamps were first introduced, the amalgam not held in a vaporized state remained condensed in an
external reservoir located in the coolest part of the lamp. If the lamp was vibrated by winds or passing traffic,
amalgam from the reservoir would splash down onto the arc tube, causing a thermal shock that would extinguish
the lamp. The lamp would then go through its start-up process and cycling would occur. Because of this thermal
blink-out problem all but one of the major HPS lamp manufacturers have abandoned the external amalgam reservoir design in favor of internal reservoirs that do not create a thermal blink-out condition.
Experience has shown that during the first 20 minutes or so of HPS lamp operation, the lamp voltage may rise or
fall from start to start, or even during continuous operation, as varying amounts of amalgam enter the arc
stream.
Most HID lamps use a wire support frame to protect, cushion, and align the arc tube in the center of the bulb.
The design and placement of this support frame is particularly important in HPS lamps, because it can affect the
temperature of the arc tube and end caps. As we have seen, arc tube temperature has a direct effect on the
amount of amalgam vaporized.
The construction and composition of the HPS main electrodes also are very critical. Material discharged from the
electrodes during start-up and operation redeposits on the arc tube ends. This blackening of the arc tube also
will increase operating temperatures and voltage across the arc tube.
Page 8
HPS End-of-Life Voltage
With a number of factors contributing to HPS lamp voltage rise, the increase in operating voltage over the life of
the lamp becomes significant. The operating voltage of HPS lamps increases about 1-2 volts per
1000 hours operated. The life of an HPS lamp is dependent on the rate of lamp voltage rise. Lamp voltage will
rise until it reaches the limit of the ballast voltage available. At this point, the HPS lamp will cycle ON and OFF,
and its effective life will be over.
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HID OPERATING CHARACTERISTICS
Certain operational characteristics are common to all HID lamps. With any HID lamp, sufficient starting current
must be supplied to the lamp during the first half-minute or so of operation. Too little current results in the lamp
never warming up properly, while too much current will reduce lamp life. Too little current can be caused by an
improperly installed lamp, a bad connection or a bad capacitor, or use of the incorrect ballast or capacitor.
Due to manufacturing tolerances, individual HID lamps operate within a range of operating voltages. For example, as shown in Table 1, a 150-watt HPS lamp rated at 55 volts can have a lamp voltage range of 48 to 62 volts.
TABLE1: HPS LAMP DATA
Average
ANSI
Code
S76 35 16,000+ Hrs. 52 110 46-62 0.83 84 1.5
S68 50 24,000+ Hrs. 52 110 46-60 1.18 84 1.5
S62 70 24,000+ Hrs. 52 110 45-60 1.6 84 1.5
S62
Dual Arc
S54 100 24,000+ Hrs. 55 110 44-62 2.1 84 1.5
S54
Dual Arc
S55
S55
Dual Arc
S56 150 (100 volts) 24,000+ Hrs. 100 198 85-115 1.8 160 1.5
S66 200 24,000+ Hrs. 100 198 90-115 2.4 160 1.5
S66
Dual Arc
S50 250 24,000+ Hrs. 100 198 90-120 3 160 1.5
S50
Dual Arc
S67 310 24,000+ Hrs. 100 198 90-120 3.6 160 1.5
S51 400 24,000+ Hrs. 100 198 84-115 4.6 140 1.5
S51
Dual Arc
S52 1000 24,000+ Hrs. 250 456 210-275 4.7 350 1.5
S52
Dual Arc
1 Rated lamp life is based on 50% survival.
2 Also called open circuit
3 100 hours is lamp manufacturer specification for stabilizing light output
Lamp
Watts
70 40,000 Hrs. 52 110 45-60 1.6 84 1.5
100 40,000 Hrs. 55 110 44-62 2.1 84 1.5
150
(55 volts)
150
(55 volts)
200 40,000 Hrs. 100 198 90-115 2.4 160 1.5
250 40,000 Hrs. 100 198 90-120 3 160 1.5
400 40,000 Hrs. 100 198 84-115 4.6 140 1.5
1000 40,000 Hrs. 250 456 210-275 4.7 350 1.5
Rated
Lamp Life
24,000+ Hrs. 55 110 48-62 3.2 88 1.5
40,000 Hrs. 55 110 48-62 3.2 88 1.5
1
Rated
Voltage
Minimum
Socket
Voltage
NEW Lamp
Voltage Range
2
(at 100 Hours)
3
Nominal
Lamp
Amps
End-of-Life
Lamp Voltage
Volts
Increase Per
1,000 Hours
Life
CAUTION: Disconnect starting lead not common to the lamp to eliminate the starting voltage when checking the
minimum open circuit voltage. The starting voltage may damage your voltmeter.
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HID lamps will operate at their rated wattages only if the lamp and line voltages are nominal. Variations in lamp
and line voltages can cause a lamp wattage variation of up to 20%.
Page 10
HID lamps should not be operated at higher-than-rated wattages. This can be caused by using a capacitor with a
rating too high for the fixture, or by installing a lamp with a lower wattage rating than the fixture. Although light
output may increase, the excess wattage dramatically increases operating temperatures of electrodes, arc tubes
and bulb walls. The arc tube may bulge and possibly shatter. Lumen maintenance and lamp life also are significantly decreased.
HID lamps also are sensitive to voltage interruptions. If the lamp circuit is turned OFF, a momentary power outage occurs, or the lamp voltage drops below the level needed to sustain the arc discharge, the ions in the arc
tube deionize and light output stops. The lamp will not restart immediately. This is because the arc gases are
now under pressure and the lamp must cool sufficiently to reduce the vapor pressure to a level where the arc will
restrike at the available voltage. The time required to relight is strongly influenced by the design of the luminaire,
since this will determine to a large extent the cooling rate of the lamp. In general, mercury vapor lamps will relight in 8 to 10 minutes, metal halide lamps in 10 to 45 minutes, and HPS lamps in 1 minute or less.
HID LAMP LUMEN MAINTENANCE
Light output from all types of HID lamps gradually declines over time. Lumen maintenance depends on a number
of light loss factors. These include any physical changes in the lamp, such as electrode deterioration, blackening
of the arc tube or bulb, shifts in the chemical balance of the arc metals, or changes in ballast performance.
Longer burning cycles result in better lumen maintenance because there is less stress on lamp components due
to frequent starting. Other factors affecting lumen depreciation are lamp watts and current, and the current waveform that is a function of the lamp and luminaire circuit. Ambient temperature does not have a great effect on the
maintained light output of HID lamps.
HPS Lamps
HPS lamps have excellent lumen maintenance (Figure 5A). HPS lamps still are generating 90% of initial light
output at the midpoint of their life span. Lumen maintenance at the end of life still is excellent at around 80%. ed
light output of HID lamps.
Metal Halide Lamps
As the graph in Figure 5B shows, the light output of metal halide lamps declines more rapidly than either HPS or
mercury vapor lamps. Frequent starting will shorten metal halide lamp life.
Mercury Vapor Lamps
Frequent starting or lamp burning position has very little effect on mercury vapor lumen maintenance.
HID LAMP LIFE
The rated average life of HID lamps is the life obtained from a large group of test lamps burned under controlled
conditions at 10 or more burning hours per start. It is based on the survival of at least 50% of the lamps or
groups of lamps and can vary considerably from the average. Factors affecting HID lamp life include: lamp operating wattage, lamp operating temperature, ballast characteristics, line voltage and burning hours per start.
Lamp age, or the number of hours a lamp has operated, has very little effect on lamp start ability, although metal
halide lamps can require longer starting times as they age.
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A B
Figure5. HID lamp lumens maintenance curves: (A) Metal Halide, (B) HPS
A B
Figure6. HID lamp life curves: (A) HPS, (B) metal halide
HPS Lamps
As shown in the lamp survival curve in Figure 6B, HPS lamps have a long average life span of 24,000 plus
hours. Normal end of life occurs when the lamp begins to cycle on and off due to excessive lamp voltage rise.
More frequent starts will cause voltage to rise faster, as will over wattage operation. Slight under wattage operation will have no adverse effect on lamp life.
Metal Halide Lamps
Metal halide lamps have an average-rated life span of 3,000 to 20,000 hours, depending on lamp wattage. Lamp
life generally is much shorter than HPS and mercury vapor due to poorer lumen maintenance and the presence
of iodine compounds in the arc tube. The normal failure mode is the inability to start because of increased starting voltage requirements. Frequent starting also will adversely affect lamp life, as will over wattage operation.
Mercury Vapor Lamps
Mercury lamps should be replaced before they burn out due to decreases in lumen output. Frequent starting
does not adversely affect lamp life as significantly as other HID lamps. The normal mode of failure is the inability
to start.
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THE HPS LUMINAIRE
Troubleshooting and repairing HPS lighting fixtures involve working with some components and operating principles not found in mercury vapor or metal halide fixtures. Now that you understand the primary differences be-
tween HPS, mercury vapor, and metal halide operation, it’s time to discuss how these differences affect trouble-
shooting and repairing procedures.
HPS Lamp Starters
Inspection of an HPS luminaire will reveal an additional component not found in mercury vapor or metal halide
fixtures—an external starter (Figure 7). This starter can be found as a printed electronic circuit board in some
luminaires. The starter also may be packaged in a small plastic cube or can. Regardless of how they are packaged, external starters all perform the same function: they increase the 120 or 240 volts supplied to the lamp to
the 2500 to 4000 volts needed to start the lamp.
Note: 1000-watt HPS lamps require a minimum starting voltage of 3000 volts and a maximum of 5000
volts. As explained earlier, this high-voltage spike is needed to bridge the wide gap between the HPS
lamp’s main electrodes.
The starter is used only during the first few moments of lamp start-up. Once the starting gas arc is struck between the main electrodes, the starter turns OFF and does not operate until it is needed again. Many service
technicians unfamiliar with HPS starter operations are unaware of this fact. They automatically replace the
starter when faced with an HPS lamp that cycles ON and OFF, particularly if the cycling is intermittent. The technician assumes the starter is at fault. In fact, it is operating repeatedly—it is turning the lamp ON not once, but
many times. The external starter must be properly matched to the lamp, luminaire and ballast. There are slight
design and operating differences between starter manufacturers, and mixing starters could result in unreliable
starts. There also are differences in the various wattage match-ups provided by the fixture manufacturers.
Therefore, mixing various wattage ballasts with various starting circuits is not recommended as this also could
result in unreliable starting.
Starter Operation
An HPS starter operates similarly to an automotive
breaker point ignition system. The ignition system is
made of two interconnected circuits: the primary (low
voltage) circuit and the secondary (high-voltage) circuit. When the ignition switch is turned ON, current
flows to the ignition coil’s primary winding, through
the breaker points, to ground. This low-voltage cur-
rent flow in the coil’s primary winding creates a mag-
netic field. When the current flow is interrupted as the
breaker points open, the magnetic field collapses,
and a high-voltage surge is induced in the coil’s sec-
ondary winding.
Figure7. Starter circuit in typical HPS circuit.
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