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Discussion Starter #1
Anyone know how much the amperage of a ballest for a 100w high pressure sodium lamp WITHOUT power factor correction capacitor would DECREASE with the addition of the recommended capacitor?

today we discovered that the fixtures that were supposed to be 208v 100w HPS

were sent as 120 volt .And then I thought it was no big deal with 8 of them being
800 watts.haha. then I remembered what our supply house did to us several years ago and checked the listed line current. Bang! No optional power factor correction capacitor ordered and the current is 2.5amps ! That's a problem.so we're having the supply.... what a mess.

How much a decrease will we see with cap?
 

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Maybe it does both things ?

And I know for sure it does effect the current
Just not sure by what amount
Inductors cause lag in the current, Caps correct the lag, but if he is talking about one cap per fixture, it's to assist in starting the lamp
 

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Last year I found out the hard way that for reactor ballasts is to use the specified capacitor MFD or you can run the current up to over double and overheat the ballast, I used a 24 mfd on a 250 watt lamp and drew over 5 amps, put in the spec'd 12 mfd and it dropped to 2 amps.

This is the difference that I found:
A Reactor (R) Ballast needs a capacitor to start the lamp,
A High Reactance Autotransformer (HX) Ballast uses a capacitor for PF correction only and is optional in many cases. They can correct from 50% up to 90%.

forgot to say: a PF cap has no appreciable affect on current, even the household CFLs only have a PF of 50%.
 

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Thought that cap was to help in starting that lamp, not PF correction
Depends on the ballast, but nearly all of them help with power factor.

Ballasts come in several types:

Lamp regulation and power factor via cap:

1. CWA

2. CWI

3. 3 coil magnetic regulator

These always come with a cap as it essential to the circuit.

Power factor correction only:

1. reactor (single coil) R-HPF

2. autotransformer reactor/ high reactance lag HX-HPF


In these a cap is often optional as not essential to lamp regulation, only power factor.
 

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Discussion Starter #9
These fixtures are simple reactor type. I experienced this issue years ago but forgot the exact amount the current would have been reduced with cap. But I do remember reading the label and seeing that without that cap we would need additional circuits for this large parking garage and this is the problem now with a private 800' driveway to apartments. 8 of these 100w hps fixtures are going to draw 20 amps and the wires were already pulled but someone screwed up the ordering of the fixtures. They were supposed to be 208v.
 

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How is it possible for 800 watts at 120 volts draw more than 8 amps?

as I said earlier when using the wrong cap which is wattage determined the amperage can more than double.

I just looked up capacitors for a HPS 100w and it says to use 10MFD, what size caps are you using?
 

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Discussion Starter #11
The lamps are 100w hps but the ballasts are cheap reactor type with NO capacitor and low power factor and high reactive power and the listed line current is 2.5 amps. It shows optional capacitor across the line but doesn't state how its inclusion with reduce line current.

I know what this capacitor will do by experiencing this before.
 

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Discussion Starter #12
Since I'm stuck inside during a massive snow storm with 60+ mph winds

I just found a table from Econolight ballasts that shows line current with normal power factor ballast at 2.15a and 1.1a with high power factor ballast.
 

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These fixtures are simple reactor type. I experienced this issue years ago but forgot the exact amount the current would have been reduced with cap. But I do remember reading the label and seeing that without that cap we would need additional circuits for this large parking garage and this is the problem now with a private 800' driveway to apartments. 8 of these 100w hps fixtures are going to draw 20 amps and the wires were already pulled but someone screwed up the ordering of the fixtures. They were supposed to be 208v.
Is the voltage 120 to the fixtures?

The ballasts/fixture should have an ANSI code, but most 100 watt reactor ballasts take a 36 MFD capacitor.
 
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