Is yr 250watts MH really drawing 250watts?

[BarraCuda™]

Many take it for granted that the wattage rating on their equipment is the same wattage that they use. You are very very wrong ... most equipment like pumps/ballasts state their "true power" (e.g 250watts) That means a min of 250watts is needed to work but is the total wattage drawn from the powersupply the same 250watts???


Most likely not, the power (apparent power) drawn from the powersupply is often higher than what is needed. E.g The 250watts may actually draw 330watts from the powersupply.


In the next few days .. I will share with you guys. What is powerfactor and how correcting powerfactor can give you significant savings.

Btw .. I just measured my resun MD55 is operating at 207watts but the actual power used is only 130watts! That is abt a waste of 70watts!

[ReDDeviLs]

WHAT!!!!!!!!!!!!!!! I just got a md55!!!!! HELP!!!!

[spsman]

hi barra,
great. pls inform us on the power factor and how to save electricity bills.

in layman terms,
mh requires high temp to burn. due to gas in the tube. and high temp is derived by wattage consumption. the ballast basically steps up. the ignitor just starts the bulb.
and the capacitor basically acts as a circuit protector.

The old and new bulbs are burning at different temps thus a discrepancy has incurred.

so the way to temper the entire lighting system could be by
1) tempering the ballast

there is this commercial device on sale on using the power factor to minimise cost. it is said to minimise all electrical appliance consumption. someone offered to sell it at $135 at pasir ris resort. well, i have seen it but not experimented on it yet. becos i am really unfamiliar with electrical works.
but seriously, after seeing explosive electric kettle and thermos flask, not forgetting the burnt overhead filter incident in S,pore that burnt the house last year. it really makes me wonder how things really work.

[ReDDeviLs]

i came across this too,infact my mum spotted that.. it claim to cut down like 30% of total electricity if my memory doesnt fail me.
but i dont really trust that. anyone came across that?
if really can work,i know where to get.

[BarraCuda™]

The ballast is just a current limiter, as MH bulbs got negative resistance so if you operate the bulb without a ballast, the MH will blow up due to the excessive current.

The ignitor is to provide the striking voltage from 2000V to 4500V needed to ignite the bulb. It also mantain the voltage needed to operate the bulb.

The capacitor is the key thing here, its a shunt capacitor. It works by countering the inductive load with reactive load. The overall result is lower apparent power and higher powerfactor. This also means that less power consumed and less heat.

[spsman]

so are u manipulating the capacitor..? sure intd to learn from u.

i will follow this thread. thks pal

[BarraCuda™]

I measured the ampere of a single 250watts using a 20uF shunt capacitor.
http://www.arofanatics.com/members/barracuda/powerfactorcorrection/image01.jpg

1.67A x 230V = 384.1watts !!

Instead of drawing only ~1.1A (250watts) .. its drawing an actual 1.67A .. that is a wastage of 134.4watts!!


To calculate the power factor .. we take true power / apparent power = 250/384.1 = 0.65.
This meant that 35% of the power drawn are not used for the lights but to heat the wiring/ballast!


Here are the new and old capacitors
On the left is the 25uF and right is the old 20uF capacitor. I'm going to use new 25uF capacitor for a comparison.

http://www.arofanatics.com/members/barracuda/powerfactorcorrection/image03.jpg








http://www.arofanatics.com/members/barracuda/powerfactorcorrection/image02.jpg

After changing the capacitor, the ampere drawn is 1.35A

1.35A x 230V = 310.5watts

384.1watts - 310.5watts = 73.6watts
Just by changing the capacitor .. I saved 73.6watts!


I took the total power consumption by the 2x250watts MH
http://www.arofanatics.com/members/barracuda/powerfactorcorrection/image04.jpg


2.58A x 230V = 593.4watts

To get the power factor - 500watts/593.4watts = 0.84

So I have corrected the powerfactor from 0.65 to 0.84 .. what does it mean??


Using 20uF capacitor
384.1watts x 2 bulbs = 768.2watts


Using 25uF capacitor
593.4watts

reduction in power consumption
768.2watts - 593.4watts = 174.8watts



Now covert all these figures into $ savings
Assuming 10hrs of light per day and 30days per month

174.8watts x 10hrs = 1748Wh = 1.748kWh
1.748kWh x 30 days = 52.44 kWh

Tariffs now is at $0.1685/kWh
52.44kWh x $0.1635 = $8.57/month



This might not be much savings .. but what if its yr high powered chiller or pump?? ;)
Next .. I will try to correct the powerfactor of the resun MD55

[spsman]

Do not type in caps!! - Edited by BarraCuda™

[SGRay]

wow! so by changing to capacitor we can save money?? will the light intensity be compromised?? Lowering the current might be lowerring heat output and light output simultaneously, thus decreasing the PAR.. how do we know that it is only lowering the heat output?? for all we know the light may be less bright.. but maybe it's not visibly apparent but PAR may have dropped???

[BarraCuda™]

wow! so by changing to capacitor we can save money?? will the light intensity be compromised?? Lowering the current might be lowerring heat output and light output simultaneously, thus decreasing the PAR.. how do we know that it is only lowering the heat output?? for all we know the light may be less bright.. but maybe it's not visibly apparent but PAR may have dropped???
Nope, I did not reduce the current intake. All I did is to correct the powerfactor by changing the impedence. The reactive power will counter with the apparent power to shift the powerfactor closer to 1.

The actual intake is 380watts while the bulb only consume 250watts .. so where the excess power go? It goes into heating the ballast and wiring.

The reason why I did not aim for a PF 1 its because the ballast, ignitor and capacitor also consume power, if you over do it .. the PF will be reduced.

[aws]

Seldom logged into this forum, just happened to saw this thread. My ballast manufacturer actually specified the size of the caps to use. I am using 250W and the specified cap value is 32 micro farad. MKP type, which is metallised pp, not the oil type.



Nope, I did not reduce the current intake. All I did is to correct the powerfactor by changing the impedence. The reactive power will counter with the apparent power to shift the powerfactor closer to 1.

The actual intake is 380watts while the bulb only consume 250watts .. so where the excess power go? It goes into heating the ballast and wiring.

The reason why I did not aim for a PF 1 its because the ballast, ignitor and capacitor also consume power, if you over do it .. the PF will be reduced.

[BarraCuda™]

Seldom logged into this forum, just happened to saw this thread. My ballast manufacturer actually specified the size of the caps to use. I am using 250W and the specified cap value is 32 micro farad. MKP type, which is metallised pp, not the oil type.
that is the probelm, different ballast got different requirements and efficiency .. thus the shunt capacitor have to be measured and calculate on a case by case basis.

[ReDDeviLs]

wow very interested in this!
hey boss so to reduce the power used,i need to change the ballest?

[Jeffrey74]

wow very interested in this!
hey boss so to reduce the power used,i need to change the ballest?
Bro I think is the capacitor that need to be change not the ballast.;)

[ReDDeviLs]

where will it be located? sorry man im an idiot in this.
the elect bill is killing me,its the main reason stopping me for a chiller! arhg!!

[jellyfish]

Hi barra? if eballast is use, will the efficiency level increase? cause eballast produce less heat and it uses electrical parts to drive the lamp compare to metal ballast uses coil...

[BarraCuda™]

Hi barra? if eballast is use, will the efficiency level increase? cause eballast produce less heat and it uses electrical parts to drive the lamp compare to metal ballast uses coil...
yes .. the efficiency of eballast is definitely better than iron core ballast. I'm currently awaiting some replies from singapore power

[slcw]

yes .. the efficiency of eballast is definitely better than iron core ballast. I'm currently awaiting some replies from singapore power

say boss,

so do u know which type of equipments is having wastage?
is arcadia MH 110cm one of them?
and Resun CL280?

[BarraCuda™]

say boss,

so do u know which type of equipments is having wastage?
is arcadia MH 110cm one of them?
and Resun CL280?
I'm not sure of that .. unless actual measurements are taken.

[ReDDeviLs]

i think most of them have wasteage..just that alot or little?

[cwloo]

yes .. the efficiency of eballast is definitely better than iron core ballast. I'm currently awaiting some replies from singapore power


what type of reply u are waiting for ?
I remember last time that's a artical about how PUB charge us ... I remember it said that the power factor is not really taking into consideration. PUB only have rules for big power eater like factory/machine to have at least a power factor of 0.7++ (can't remember the figure) to maximise the usage.

Also, those power saver selling outside which claim saving of 30% in your PUB bills is not true . The saving is only 5%+- I think , CASE stop a company from misleading customer few months back.

[BarraCuda™]

what type of reply u are waiting for ?
I remember last time that's a artical about how PUB charge us ... I remember it said that the power factor is not really taking into consideration. PUB only have rules for big power eater like factory/machine to have at least a power factor of 0.7++ (can't remember the figure) to maximise the usage.

Also, those power saver selling outside which claim saving of 30% in your PUB bills is not true . The saving is only 5%+- I think , CASE stop a company from misleading customer few months back.
Yes .. indeed. ECC confirmed that the electrical charges are based on active power and not apparent power. So it might not be able to save you much $ afterall :p

But, correcting the powerfactor will reduce the reactive load (especially impt for poor quality extension/timers/old MCB). We are not charged for the reactive power but the reactive load is still on the circuit. That will heat up the circuit, higher voltage drop and may melt poor quality timers/extension.

For safety reasons, its still good to mantain a good powerfactor to ensure that the entire electrical system is not overloaded by reactive power.

[slcw]

Yes .. indeed. ECC confirmed that the electrical charges are based on active power and not apparent power. So it might not be able to save you much $ afterall :p

But, correcting the powerfactor will reduce the reactive load (especially impt for poor quality extension/timers/old MCB). We are not charged for the reactive power but the reactive load is still on the circuit. That will heat up the circuit, higher voltage drop and may melt poor quality timers/extension.

For safety reasons, its still good to mantain a good powerfactor to ensure that the entire electrical system is not overloaded by reactive power.

oh...but not much ppl would bother about that esp in m'sia

[ReDDeviLs]

in sg there is alot of accident with fire due to fish rearing during the luohan craze.
i think thats very important..

[cwloo]

Dig out this thread again ... Anyone know how to measure active power ? Is there a meter around that can measure that ?

[BarraCuda™]

Dig out this thread again ... Anyone know how to measure active power ? Is there a meter around that can measure that ?
true RMS watt meter or watt-hour meter but they are expensive :(

[cwloo]

true RMS watt meter or watt-hour meter but they are expensive :(
er .. how expensive is that gonna be ... *may* have the budget from the company... :p

[BarraCuda™]

er .. how expensive is that gonna be ... *may* have the budget from the company... :p
digital meters should be in the hundreds range

[cwloo]

Bro .. just one question.

If you use a 50 uF capacitor, will it further improve the power factor ?

[BarraCuda™]

Bro .. just one question.

If you use a 50 uF capacitor, will it further improve the power factor ?

Looking at the 25uF range, if you use >50uF, you are likely to overcorrect the powerfactor which again results in less efficiency.

If you are sway enough to hit the sweet inductance/capacitance resonance, it will cause it to have a impedence of 0 resulting in a huge surge of current flowing to yr lights. This will likely to cause explosion/fire/burnt out.

[IanJ]

I think if you view the bulb/ballast comparison data available on USA websites, it is clear that electronic ballasts run the bulbs at a lower wattage, this tends to be reflected in the brigtness of the bulb. the HQI ballasts draw more watts and are brighter.
Is that not correct?

[BarraCuda™]

I think if you view the bulb/ballast comparison data available on USA websites, it is clear that electronic ballasts run the bulbs at a lower wattage, this tends to be reflected in the brigtness of the bulb. the HQI ballasts draw more watts and are brighter.
Is that not correct?

All manufactured products have tolerances, the same brand/model may not have the same measurement. Electronic ballast have higher efficiency in the sense that they have a higher powerfactor, it simply means that less reactive power is used.

Its not recommended that bulbs should be overdrived. It will only shorten the lifespan and risk failure with that little extra brightness.