120v verse 277v
120v verse 277v
(OP)
Just left meetings with an Industrial lighting manufacture sale rep and He quoted “there is no difference between 120v to 277v ballast.” The difference I was concerning myself with was the operating cost. I believed the 277v version was cheaper to operate because of the reduced amps and watts. His explanation was they are both produce the same thing in the end and that what really mattered.
thank you
2571
thank you
2571





RE: 120v verse 277v
Power = Volts x Amps
You can screw with the V and the A all you want as long as the P stays the same.
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: 120v verse 277v
2571
RE: 120v verse 277v
RE: 120v verse 277v
But, for the lighting system as a whole, as OperaHouse says, 277 V could be more efficient due to lower current in the lighting circuit and thus reduced losses in the wiring.
RE: 120v verse 277v
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Sometimes I only open my mouth to swap feet...
RE: 120v verse 277v
Your watts per circuit can also be 2.3 times greater at 277 V compared to 120 V at the same current.
You save on wire, breakers and panel space.
respectfully
RE: 120v verse 277v
RE: 120v verse 277v
BTW, the ballast that runs on 277 or 120 is a multi-tap unit, meaning that it has different winding taps brought out from the transformer that are connected for each respective input voltage.
RE: 120v verse 277v
Please explain this further. 'More efficient' with reference to what, and how is the efficiency improvement brought about?
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Sometimes I only open my mouth to swap feet...
RE: 120v verse 277v
I believe the efficiency being referred to by AllorNothing was intended to describe the overall system efficiency in using the available power, not the ballasts themselves.
While it is quite true, as noted by Keith (itsmoked) that:
"Power = Volts x Amps
You can screw with the V and the A all you want as long as the P stays the same."
keep in mind that Keith was speaking of the ballast which has relatively low internal resistance. When dealing with the overall lighting system, efficiency is greatly affected by power lost in the transmission of the total power throughout the wiring of the system.
For example, let's say the lighting system has a Total Power of 1,000 Watts delivered into it at the source. That Total Power could be any combination of Volts x Amps that equals 1,000 Watts, just as Keith stated. 100 Volts at 10 Amps would provide the same total power as 50 Volts at 20 Amps at the input to the lighting system.
What proportion of the Total Power will be actually used for the intended purpose (providing light) in the lighting system is 1,000 Watts MINUS the power lost in the transmission lines. Since the power wasted in losses is equal to the Amperage squared times the Ohms (resistance) of the transmission lines (the wires), reducing the Amperage component reduces the lost (wasted) power expotentially (the Amperage squared term). In other words, because Total Power = Volts x Amps, BUT the Wasted Power = Amps (squared) x Resistance, the proportion of the Total Power that gets lost as Wasted Power decreases expotentially as the Voltage component increases and the Amperage component decreases.
So the higher voltages quoted by AllorNothing in their post result in lower amperages, further resulting in less Wasted Power in transmitting the Total Power thoroughout the lighting system. As you previously stated, this assumes the wire size (or more accurately, the system Resistance component) stays the same. Changing wire size can affect overall system efficiency as well by changing the Resistance component.
Best regards,
debodine
RE: 120v verse 277v
debodine
RE: 120v verse 277v
The only one I could readily add to those already mentioned was that the switching components in an electronic ballast would possibly have lower losses at a higher supply voltage, but that I wouldn't be certain of that because the higher voltage rated switches usually have higher on-state losses.
AllOrNothing is welcome to comment further.
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Sometimes I only open my mouth to swap feet...
RE: 120v verse 277v
Do the math on a system, you will be amazed how much it will cost over the course of a year.
Plus, at today's copper prices, every foot of conductor you can save is good.
RE: 120v verse 277v
Is the consensus that efficiency of the ballast doesn't change significantly regardless of whether it is fed at 120 / 277 / 480V, even if the efficiency of the overall installation may improve?
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Sometimes I only open my mouth to swap feet...
RE: 120v verse 277v
RE: 120v verse 277v
However the cost of operating must include the cost of losses in the wiring from the revenue meter to the ballasts and there will definitely be reduced costs overall, both in the initial installation and operating costs with a 277 volt system.
respectfully.
RE: 120v verse 277v
RE: 120v verse 277v
RE: 120v verse 277v
If you have 277V readily available for lighting use it. There are a couple of different reasons. If 277V is available, your installation costs with 277V will be lower because of reduced wiring and breaker count and such. Also, since you will have fewer amps running in building wiring you will save a little there. From an efficiency standpoint, 277V ballast will tend to have a slight edge over 120V units but not by much.
Another consideration is that manufacturers tend to build alot more 277V ballast than they do 120V units.
BTW if you are powering flourescent lighting I would look closely at electronic ballasts. They are more expensive up front but will pay for themselves quickly as they are considerably more efficient for flourescents.
RE: 120v verse 277v
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: 120v verse 277v
I have seen electronic ballast for HID lighting but don't think they are much if any more efficient than magnetic for HIDs. Most of what I have seen electronic HID ballast for is some type of special application.
The efficiency gain in fluorescents is a result of the operating frequency and physics associated with the lamp. Above about 10kHz to 12kHz the physics of developing a discharge in a fluorescent lamp changes. At higher frequencies it becomes easier (i.e. less power) to cause the electrons in the fluorescent lamp to change energy state and release photons. This phenomenon begins to plateau around 15kHz to 20kHz. For a 4ft, 32W, T8 type lamp an electronic ballast operating at about 25kHz will produce the same amount of light as a magnetic with only about 25W instead of 32W.
RE: 120v verse 277v
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com