Design of HID transformers: HPS and MH

In summary: This is my first post, and I hope I've found the right area to pose my question. As background, I don't have very much experience with HID applications, though I have extensive experience with general electrical wiring and systems design. Some manufacturers sell ballasts that can handle both types of bulbs, and have a switch which drops the igniter out of circuit for MH or includes it in circuit for HPS bulbs. While there are slight differences between the electrical outputs of regular HPS and MH cores, they are not outside of the operational limits of either bulb. Thus the 'switchable' transformers.
  • #1
stevenwright
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This is my first post, and I hope I've found the right area to pose my question. As background, I don't have very much experience with HID applications, though I have extensive experience with general electrical wiring and systems design.

My question is this:
The difference between a metal halide transformer and a high pressure sodium transformer is that an HPS 'ballast' has an igniter to keep the arch tube lit, while a MH does not. Some manufacturers sell ballasts that can handle both types of bulbs, and have a switch which drops the igniter out of circuit for MH or includes it in circuit for HPS bulbs.

While there are slight differences between the electrical outputs of regular HPS and MH cores, they are not outside of the operational limits of either bulb. Thus the 'switchable' transformers.

What I don't understand is why a metal halide core can't be used to operate HPS lamps. Obviously, to run a MH lamp with an HPS ballast you take the igniter out of circuit. But where would you add an igniter in an MH ballast?

The schematics describe the igniter being attached between the "X3" wire and the lamp wire. I believe that simply attaching an igniter in line with the lamp wire on a MH will allow an HPS lamp to be operated. My theory being that the "X3" is simply an extension of the lamp wire.

Am I totally off base here? Can someone please help me with this question? Thank you very much, and I'm glad to have found such a wealth of information.
 

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  • #2
stevenwright said:
What I don't understand is why a metal halide core can't be used to operate HPS lamps.
Maybe you can.

https://en.wikipedia.org/wiki/History_of_street_lighting_in_the_United_States#Metal_halide said:
In response to the ban, some older MV streetlights will most likely be modified to use either high pressure sodium or metal halide lamps in the near future, because they are known to last longer than newer luminaires. In some areas where the MV lights are either failing or being replaced, they are being replaced by either HPS, LED, or Induction fixtures of similar lumen output, but also lower wattages and power consumption as well.
 

1. What is the purpose of a HID transformer?

A HID (High-Intensity Discharge) transformer is used to regulate and control the electrical current that powers high-intensity discharge lamps, such as HPS (High-Pressure Sodium) and MH (Metal Halide) lamps. It converts the standard voltage from a power source to the specific voltage required to ignite and maintain these types of lamps.

2. How does the design of a HID transformer differ for HPS and MH lamps?

The design of a HID transformer differs for HPS and MH lamps in terms of the materials used and the winding configuration. HPS lamps require a transformer with a higher inductance and a larger core to sustain the higher voltage needed for ignition and operation. MH lamps, on the other hand, require a lower inductance and a smaller core due to their lower operating voltage.

3. What factors should be considered in the design of a HID transformer?

When designing a HID transformer, factors such as the lamp type, wattage, and operating voltage must be taken into account. The transformer must also be designed to withstand high temperatures and have adequate insulation to prevent electrical arcing. The size and weight of the transformer may also be important considerations.

4. How does the efficiency of a HID transformer affect its design?

The efficiency of a HID transformer is an important factor in its design. A more efficient transformer will produce less heat and waste less energy, resulting in a longer lifespan and lower operating costs. Therefore, the design of a HID transformer must aim to maximize efficiency through careful selection of materials and winding configurations.

5. Can the design of a HID transformer affect the performance of the lamp?

Yes, the design of a HID transformer can greatly affect the performance of the lamp. A poorly designed transformer can cause the lamp to flicker, have a shorter lifespan, or even fail to ignite. It is crucial to carefully design and test HID transformers to ensure optimal performance and longevity of the lamp.

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