Frequency  sensitive  lamps
 

RE: Frequency Sensitive Lamps 50Hz or 60Hz?

The electrical power supplied to the countries of the world is typically 50Hz or 60Hz.  The electric power frequency is shown in the number of hertz (cycles per second).  This means that the flow of the electrons switch or reverse polarity 50 or 60 times per second. The United States for example is 60Hz. Other parts of the world are 50Hz. This is to say that when we sell a lamp for the U.S. market, we assume that the power supply that drives this lamp will be 60Hz.  By the same token, when we sell a lamp to a country with 50Hz power, we assume that it will be operated on a 50Hz source.  Here is a great website that you can refer to on this subject.

http://electricaloutlet.org/

Medium pressure mercury vapor and metal halide lamps have a few quirks and one of them is that they can be, depending on the arc length, frequency sensitive.  

FOR EXAMPLE - - -  
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LAMPS RUNNING AT 60HZ
Lamps with arc lengths from 900mm to 1120mm and 1800mm to 2240mm can have plasmas that wiggle and become unstable.   We will need to know at time of order which frequency they are operating at.   Metal halide lamps operating at 60Hz, can not be produced within these arc lengths.
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LAMPS RUNNING AT 50HZ
Lamps with arc length from 1170mm to 1420mm and 2340mm to 2840mm can have plasmas that wiggle and become unstable.   We will need to know at time of order which frequency they are operating at.   Metal halide lamps operating at 50Hz, can not be produced within these arc lengths.

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The condition with the plasma arc wiggling or snaking is commonly referred to as acoustic arc resonance.