Kill-A-Watt user. Please help

[Mchava]

Okay so I got my hands on a meter today and I tested my tanks equipment. The question I have is, do I take the watts reading as my true watts or do I take the VA number as my watts? I can seem to figure it out. When I checked my mag9.5 pump is says iam using only 59w but at a 1.08amps when I hit the watts button again it reads 123-125 which is about right when I take the volts X amps. Well here are some reading let me know what you think. Thanks in advance.
Mario


Item watts Amps VA
M9.5 59 1.08 125
1260 33 .61 71
6080 25 .31 36
7400 27-41 ? ?
1/10chl 250 3.17 364
Fan 14 .25 29
250mh 290 3.30 330
MJ1200 10 .30 34

 

[bennyinca]

Mario, I think you also need the PF (power factor) number

 

[Mchava]

you know I did not even take a measurement of that. Every time I pressed that button it always showed 59.9hz and I cant remember the other but it never realy changed at all. So how would I go and find out how much watts its realy using? Can you help me out? thanks

 

[cthetoy]

Sorry to interrupt this thread but was wondering the same as well. What I wanted to know is what SCE uses to calculate your energy usage. Is it watts, VA, amperage, or power factor?

 

[bennyinca]

Mario, if I recall: Volts is always going to be in the 120V range, and Hz in the 59.9 Hz range.

The rest is measured. in your mag pump's case:
Item watts Amps VA
M9.5 59 1.08 125

VA = Volt x Amp = 120 x 1.08 = 129W
Watt used = 59 = VA x PF . In this case I am guessing the PF for this pump is 0.45 range? 129W x 0.45 = 58 W
That means the pump draws 1.08 amp, but is somewhat efficient, and is using 58W. Multiply the 0.058 KW by the number of hours the pump is using, and you get KWh, which is the unit SCE uses to charge.

Maybe someone with engineering background can clear this in case I am wrong.
HTH

 

[dpstrand]

They charge in terms of KWH (kilowatt hours). 1000 W = 1 KWH. There is actually a kwh measurement on the kill-a-watt.

 

[Mchava]

okay I see now I need to find out what the PF is to calculate how much true watts it is using some if iam correct lets see the mag9.5 is costing me: .058*24hr=1.392kh/d=1.392*22days=30.624/m=30.624*~$.12=$3.67/month
so the pump will cost ~$3.67 to run per mont right.

 

[dpstrand]

Yeah if it is a motor, it is an inductive load. You are right on the equations, power factor is the ratio of "actual" power to "apparent" power. Inductive loads are actually less efficient from a power delivery point of view, it takes them 129W of total energy to keep your pump spinning, but SCE only charges/measures residential customers the actual power (58w in your case).

It's been a long time since my power classes, so I might not be explaining this very well.... but you just take the watts reading divided by 1000 and multiplied by hours per day to get KWH per day.

 

[Mchava]

so iam actualy saving money but iam costing them more to run my tank. Is that why a regular light bulb has a PF of 1 which means that it used 40w and I get charged for 40w where as the pump is used on 1/2 the watts but needs more to run. Is this correct?

 

[Mchava]

so let say my MH lighting system is 300watts drawing 3.30amp w/ a pf of .89 that meens:

115*3.30=379.5w 330*.89=293Twatts
293w*10h=2930w/1000= 2.93kw/d
2.93kw*22d=64.46kh/m
64.46kw/m* $0.12=$7.75/month MH*2=$15.50

That is of course assuming I dont go over baseline then its more.

 

[laverda]

You should run each device for a while so you can get the KWH then you devide it by the number of hours you tested it. the meter will give you both of those figures. I try to run every thing for 6-24 hours, to get real accurate numbers. to get the PF reading you have to hit the button for it twice. The first time you hit the PF button it reads HZ, the second time it reads PF. You really should record everything as voltage can very a few volts. HZ varies the least. KWH/hours is what you really want to know, and you have to leave the meter on for a little bit to get a accurate reading.

 

[dpstrand]

I agree, KWH read directly from the kill-a-watt over the course of a few days (it will store up to 99 hours worth if I remember right).

In you $ per month calculation, why do you multiply by only 22 days? The number of days fluctuates with the month, but never down to 22, typically 28-31.

 

[Mchava]

our last bill was for only 22days not sure why and since I dont keep the originals I dont know what the montly billing cycle is.

 

[laverda]

If you guys with kill-A-watts will send me complete data I would like to compile a data base of what reef equipment uses how much current. Please include make and mode of the pump and how many GPH is is supposed put out at what height. If the data is not complete it is not going to be of much use. I will post it and update as I get more information. Please email it to me with the subject line Kill-a-watt. Steve

 

[Mchava]

I will see what I can do. I will start with my return pump and skimmer since that is what I use alot. I will also test my MH fixture tomorrow. I dont know if I can do the chiller cuase its connected to the acjr and it will turn if off once its on its set temp. I will do one hr each if that is a good measurement. If not then let me know.
mario