Difference between revisions of "Philips MHN-TD"

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Philips MHN-TD (view source)

Revision as of 13:02, 30 September 2021

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*Internal high pressure quartz discharge tube
*Internal high pressure quartz discharge tube
*RX7s base or FC2
*RX7s base or FC2
*Requires matching mercury vapour or high pressure sodium ballast
*Requires matching high pressure sodium ballast
*Requires external ignitors
*Requires external ignitors
*Color rendering index Ra of 76 to 92
*Color rendering index Ra of 76 to 92
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== Lamp control gear ==
== Lamp control gear ==
*Requires external gear (similar to mercury vapour lamps) and appropriate wiring:
* Philips BSN or compatible reactive semi-parallel inductive ballast with matching power rating
** Philips BHL or compatible reactive inductive ballast with matching power rating
* Philips SN or compatible parallel ignitor for 5000 Volt pulses
** Philips SI or compatible parallel ignitor for 5000 Volt pulses (except "S" designated lamps)
* May require power factor correction capacitor for balancing line load
** May require power factor correction capacitor for balancing line load


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== Best retro purpose ==
== Best retro purpose ==
Metal Hallide lamps are still widely used on commercial, industrial and architectural lighting but in these applications LED lamps are quickly replacing them due to much better performance, lower energy consumption and easy servicing. Light appearance is coll white or daylight, depending on lamp model, with good colour reproduction and low ultraviolet emission. The lamp can be used indoors as well as outdoors, when intense lighting is required as most surrounding look quite pleasing being light with new lamps. With the most common gear, an electromagnetic ballast along with an ignitor, flicker is noticeable.
Metal Hallide lamps are still widely used on commercial, industrial and architectural lighting but in these applications LED lamps are quickly replacing them due to much better performance, lower energy consumption and easy servicing. Light appearance is coll white or daylight, depending on lamp model, with good colour reproduction and low ultraviolet emission. The lamp can be used indoors as well as outdoors, when intense lighting is required as most surrounding look quite pleasing being light with new lamps. With the most common gear, an electromagnetic ballast along with an ignitor, flicker is noticeable.


These type of double-ended lamps were used sometimes for lighting exterior areas, especially for higher powered lamps but the most frequent application was indoor accent lighting with lower wattages. The lamp was relatively affordable (for a metal hallide lamp) and compact, having a successful niche until LED lamps appeared. Since they are very compact light sources it should be noted that heat output is very high, making the lamp unsuitable for open-air operation, seriously limiting flexibility. Another very important limitation is caused by the mandatory operating position and relatively short lamp life. While lamp warm up time is low, with the lamp achieving high output quite quickly, they are slow to restart, 10 minutes pauses not being uncommon. Both high pressure mercury vapour as well as sodium vapour ballasts can be used if provided with a suitable ignitor.  
These type of double-ended lamps were used sometimes for lighting exterior areas, especially for higher powered lamps but the most frequent application was indoor accent lighting with lower wattages. The lamp was relatively affordable (for a metal hallide lamp) and compact, having a successful niche until LED lamps appeared. Since they are very compact light sources it should be noted that heat output is very high, making the lamp unsuitable for open-air operation, seriously limiting flexibility. Another very important limitation is caused by the mandatory operating position and relatively short lamp life. While lamp warm up time is low, with the lamp achieving high output quite quickly, they are slow to restart, 10 minutes pauses not being uncommon. Both high pressure mercury vapour as well as sodium vapour ballasts can be used if provided with a suitable ignitor.


Overall, MHN-TD lamps are not great for retro purposes as the lamp is quite cumbersome to use and does not have any special features to showcase. Fixtures must be designed to house this type of lamp, meaning that a lone lamp is not a good choice and a complete system must be found. Limitations on operating positions and poor colour and lumen maintenance mean that spare lamps should be considered if long-term use is required.
Overall, MHN-TD lamps are not great for retro purposes as the lamp is quite cumbersome to use and does not have any special features to showcase. Fixtures must be designed to house this type of lamp, meaning that a lone lamp is not a good choice and a complete system must be found. Limitations on operating positions and poor colour and lumen maintenance mean that spare lamps should be considered if long-term use is required.
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Notes:  
Notes:  
* The "RX7s" base is the most popular and mounting caps can be easily found while "FC2" is a specialist items
* The "RX7s" base is the most popular and mounting caps can be easily found while "FC2" is a specialist item


== Durability and Repair-ability ==
== Durability and Repair-ability ==
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== Review ==
== Review ==
These high pressure sodium vapour lamps are compact light sources that are viable for wide area lighting. Their poor colour reproduction and large output means that they are entirely suited to outdoor lighting or greenhouses as grow light. Compared with fluorescent lamps they were very compact, having great performance at low temperatures. A very long lifetime, that was around 16 to 25 times higher than tungsten lamps, and almost double that of some fluorescent lamps, meant that these lamps are well suited for use in places where lamp replacement was costly, as in high bay lighting, street lighting, tunnel lighting.
These metal hallide lamps are well suited for indoor lighting due to their moderately high power rating and good colour reproduction. Although outdoor lighting is entirely possible, especially for higher power rated lamps, it is quite difficult to achieve. Large wattage fixtures were never as popular as those for the typical E40 base lamps, meaning that finding and using the 150 and 250W lamps is not attractive. The lamp itself fares well in terms of light output but the point light source nature of the lamp relegates it to accent or directional rather than general lighting.
 
High pressure sodium lamps had higher light output, almost double, of mercury vapour lamps while having very low quality colour reproduction. This means that mercury vapour lamps were still suited for areas where colour reproduction was moderately important and there was still an advantage from compact light sources. However, street lighting was a very important market as the lamp's efficiency ensured cost savings in labour and electricity use, after the 1970s oil crisis. There were some advances in colour reproduction with different lamp technology but standard lamps were not favourite of industrial, workshop lighting commercial premises. The light spectra was, however, highly beneficial for plant growth.
 
The inherent flicker of mains voltage lamps is very low even with conventional gear due to the fact that a large amount of light happens due to thermal emission and balance of the temperature of internal arc tube. There were some electronic medium frequency gear similar with ones used on fluorescent lamps but they were very costly. However, sodium and metal hallide gears are generally compatible, meaning that most sodium lamps can be easily replaced with compatible wattage metal hallide lamps that have a much better colour appearance, sacrificing some energy efficiency due to different lamp technology. The requirement for ignitors along ballasts while it raises total cost and increases complexity, as well as raising the risk due to passing thousands of volts through some wires, means that fixtures have a clear advantage of maximum useful light and restart in case of power failure in almost one minute.


Fixtures are generally compact, considering the light output made available, but are generally heavy due to the bulky electromagnetic gear being used. There are directional and omni-directional fixtures that are suited to various purposes. In street lighting, the well known cobra-head style lamppost was used, and they may still be available for purchase. They were only moderately effective as light covered a large area but a considerable amount of light was lost due to the fixture directing some of it upwards, with no control. Omni-directional fixtures were used in residential areas and parks, where ambience was more important than efficiency. Indoor fixtures were centered on the typical high-bay or low-bay types due to their application in greenhouses where light has to be directed entirely downwards. Other fixtures were compact, having a boxy design, with a symmetrical or asymmetrical lamp placement that was suited for flood lighting. These type of lamps were used outdoor, for floodlighting. There were no home designed fixtures as these lamps were never used in home environments.
The lamp's performance is mostly mediocre, if we consider price and technology. Much better products having longer life and better colour reproduction were manufactured, such as the ceramic arc tube Philips CDM range, meaning that MHN-TD lamps are a poor choice.  


Nowadays, sodium vapour lamps are still very widely used as outdoor lighting. As the number of available fixtures is massive, availability is high and will diminish no early than 2030s, meaning they are economically effective to purchase except and they can be repurposed for mercury vapour of metal hallide lamps if proper lamp gear is used. Free standing lamps are quite capable on their own so if you need a compact light source that is highly durable and colour output is not important. They have the additional advantage of attracting less insects during the summer, if used as outdoor light. They are especially well suited for security lighting. Of special interest is greenhouse lighting, as was mentioned before, even if specialized lamps have also been designed for these purposes, the standard lamp is also appropriate.


== Operation ==  
== Operation ==  
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The lamp requires a conventional or electro-magnetic gear of the same power output as the lamp, connected in series with a lamp and an ignitor that must be connected as is required in the circuit. Connecting the lamp directly to mains damages it instantly as there is no current limitation. Improper connection of the ignitor is also dangerous and proper care must be exerted during installation and servicing. A power factor capacitor that has a specific value might be used to correct the power factor and current requirements on the circuit. The lamp itself is not influenced by the presence or absence of this capacitor. When used sparingly in homes or some premises where not a lot of these lamps are located, power factor correction is not important but large industrial or commercial clients were required to maintain a specific power factor due to electricity distribution contracting.  
The lamp requires a conventional or electro-magnetic gear of the same power output as the lamp, connected in series with a lamp and an ignitor that must be connected as is required in the circuit. Connecting the lamp directly to mains damages it instantly as there is no current limitation. Improper connection of the ignitor is also dangerous and proper care must be exerted during installation and servicing. A power factor capacitor that has a specific value might be used to correct the power factor and current requirements on the circuit. The lamp itself is not influenced by the presence or absence of this capacitor. When used sparingly in homes or some premises where not a lot of these lamps are located, power factor correction is not important but large industrial or commercial clients were required to maintain a specific power factor due to electricity distribution contracting.  


== Suitability ==  
== Suitability ==
HPI Plus lamps are the best choice since they do not require specific fixtures for operation, their ovoid outer bulb allowing simple operation and less glare with possible operation as free standing, hanging, lamps. HPI-T lamps are much more effective for flood lighting but they require specific fixtures and have higher surface temperature, making them more susceptible to damage when improperly handled. Chinese branded lamps are much worse in all performance and quality metrics with shorter useful life, worse colour reproduction and and efficiency as a proper, stable mix of hallides required huge research investment that was too costly for Chinese producers.
MHN-TD lamps are a good choice for directional lamp fixtures. If a fixture in good enough condition is found, the lamp offers good light output that could make it useful on interior as well as exterior applications. The most popular lamp wattage seems to be the 70W type, as it was powerful and compact enough to justify the purchase of a fixture that has an elliptical light beam. Garden lighting is not the best application choice as the lamps are not as suited as the 250W and 400W types offer much higher outputs. Indoor lighting is also limited since use in living rooms is not entirely attractive as flicker is present with conventional lamp gears and the lack of hot or quick restart and average lamp performance does not justify the much costlier electronic lamp gear.
 
The best choice are, probably, the 250 watt lamps as larger powered lamps are too powerful for most purposes. This lamp wattage was also cheaper as they were highly popular. Electro-magnetic ballasts or conventional gears are plentiful and can be used interchangeably with all manufactured lamps for a specific wattage and ignitors' performance is less critical as on high pressure sodium lamps. Lower rated power output gears can be used, but it is not recommended as colour reproduction and lamp lifetime will be reduced while higher powered ones damage the lamp due to over-stressing and is highly dangerous.


Used lamp gears might work but old lamps are never desirable as they degrade much quicker than mercury vapour and sodium lamps. Rusted ballast may still operate but are a potential hazard while old, used lamps, may not have much useful life left and they may already exhibit some colour light emission issues. New old-stock lamps are the best choice, if available.
Lower rated power output gears can be used, but it is not recommended as colour reproduction and lamp lifetime will be reduced while higher powered ones damage the lamp due to over-stressing and is highly dangerous. Used lamp gears might work but old lamps are never desirable as they degrade much quicker than mercury vapour and sodium lamps. Rusted ballast may still operate but are a potential hazard while old, used lamps, may not have much useful life left and they may already exhibit some colour light emission issues. New old-stock lamps are the best choice, if available.


== History ==
== History ==
The lamp technology was an improvement of previously developed mercury vapour lamps. The potential for fluorescent powders was mostly exhausted by early 70s which meant that research concentrated on releasing better lamps that produced light directly from the discharge tube. This research was also carried previously but results were modest, as stable compounds with good colour reproduction were found to be quite aggressive and lead to short service life. Sodium, Scandium, Indium, Thallium were attempted as main elements that can offer a balanced light output but they required a specific balance of temperature and pressure to achieve best results. One major limitation was that certain compounds were costly or difficult to manufacture or mix in specific amounts, which meant that suitable results could not be found for many decades. In the late 70s and early 80s most major manufactures were able to center on specific technologies that reached good enough results for general lighting, with predictable performance.
The lamp technology was an improvement of previously developed mercury vapour lamps. The potential for fluorescent powders was mostly exhausted by early 70s which meant that research concentrated on releasing better lamps that produced light directly from the discharge tube. This research was also carried previously but results were modest, as stable compounds with good colour reproduction were found to be quite aggressive and lead to short service life. Sodium, Scandium, Indium, Thallium were attempted as main elements that can offer a balanced light output but they required a specific balance of temperature and pressure to achieve best results. One major limitation was that certain compounds were costly or difficult to manufacture or mix in specific amounts, which meant that suitable results could not be found for many decades. In the late 70s and early 80s most major manufactures were able to center on specific technologies that reached good enough results for general lighting, with predictable performance.


The market for large lamps was important as there was an interest in using more energy efficient lamps when the early 1970s oil crises brought new challenges. High pressure mercury vapour lamps were efficient but their light was not white while improvements in high pressure mercury vapour lamps were not satisfactory. While metal hallide lamps were more expensive than mercury vapour lamps, the energy savings that were around 25 to 50% meant that this technology was attractive enough considering much improved colour reproduction despite shorter lifetime. The ability to run on mercury vapour gear and the ability to retrofit these fixtures was critical to market success while the ability to run on high pressure sodium lamps ensured improvements on other installations. These are the most important factors that ensured market success as metal hallide lamps required careful installation, operation and restocking.
The MHN-TD range was the result of research aimed at creating lower powered metal hallide lamps that had better colour reproduction and energy efficiency compared with high pressure mercury vapour lamps. The most important limiting factor was that the arc tube had to be formed more evenly at the ends and be reasonably well insulated and heat resistant to ensure reasonable performance. More advanced manufacturing tools and processes had to be developed. As soon as they were available and the arc tube was well built to resist the long term corrosive nature of hallides, products were ready for release. It was also important to ensure less variations in arc tube geometry as well as temperature profile. This meant that heat reflecting coatings were mandatory for the arc tube. As soon as all these conditions were met, the lamp was released. Products were quite successful on the market until the advent of the much improved ceramic tube metal hallide lamps, around mid 1990s. Although Philips CDM lamps were much more expensive, their better colour reproduction, lamp life and efficiency meant that there was no reason other than cost to choose MHN lamps.
 
Of course, metal hallide lamps were always less successful than fluorescent lamps, especially when larger fixtures, especially indoors, were not an issue. Fluorescent lamps were easy to stock, replace, had a longer useful life and they offered custom light reproduction with great prospects for energy efficiency improvements. Lower power rating metal hallides were developed and marketed but they required specific fixtures that were able to withstand the possibility of a blown old arc tube and the high heat output and complex operating gear, along with worse flicker than fluorescent lamps. All this, along with a large price justified by complex manufacturing quality control, meant that fluorescent lamps were always more popular in most commercial and all residential applications.


LED lamps affected the most this expensive lamp and gear technology, as it quickly surpassed it in ease of use, much longer useful lifetimes, better colour reproduction and versatility in both indoor and outdoor applications. This means that the market for metal hallide lamps was quickly diminishing even quicker than high pressure sodium vapour or even the older mercury vapour lamps, both surviving longer due to lower lamp replacement costs.
The only improvement on MHN-TD lamps focused on slightly improved colour reproduction which required higher operating pressure and slightly changed chemistry to ensure stability in this environment to reach color rendering indexes Ra8 of more than 80. Philips was not interested to invest more in quartz metal hallide technology so other world manufacturers like General Electric, Osram and others quickly surpassed it with better performing products so Philips competed only mostly on cost and ensured its market-share with advertising. Even before the advent of LEDs MHN-TD lamp installations were pointless so sales were mostly based on the large install base created in the 1990s.


== Manufacturing specificities ==
== Manufacturing specificities ==
Most manufacturers have been releasing lamps for many decades and constantly improved technology so that lamps had a stabler, predictable lifetime and slightly improved colour stability due to manufacturing progress. Lamps produced in the 70s and early 80s are probably not commonly found today. In the 90s and early 2000 Philips was manufacturing lamps in Holland and other countries, while in the last years they were doing the same thing in China. Quality was not severely affected as manufacturing quality was maintained and applications were demanding, used in wealthier countries. It should be noted that there are larger differences between compatible lamps released by Osram, General Electric or other major manufacturers as each of them settled on slightly different chemistry with different reliability and performance.
Most manufacturers have been releasing lamps for many decades and constantly improved technology so that lamps had a stabler, predictable lifetime and slightly improved colour stability due to manufacturing progress. This lamp technology was almost unchanged since introduction with the only exception of moderate colour rendering improvements so other lamps, even compatible with it, from Osram, General Electric and others, were a much better choice. As Philips was focusing on cost and marketing MHN-TD lamps were much more popular and are easier to find.
 
Products manufactured by Philips were similar to General Electric and Osram, with a quality and consistency much above some East-European manufacturers in terms of colour rendering, light output and life. However, Philips was manufacturing lamps with shorter lifetimes and poorer colour reproduction than typical Osram ones, especially on standard metal hallide lamps, as Philips was focusing on cost and marketing. On the other side, Philips lamps were much more popular and are easier to find.


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