Eheim Pumps Rated Wattage False?

[OziOscar]

In some ways, I'm thankful that they took the time to answer the query in a long-winded albeit "go away" manner.

In others, it's kind of a shattering of the belief that buying the more costly German gear is worth the extra expense for the savings in the long-term. That is at least in direct-cost measurable terms for operating expense.

And in others, it's even more shattering to know that Eheim motors have an efficiency of only 50%. At work, motors with an efficiency of only 90% on some of the high performance items and a powerfactor of 89-ish%, we're already quite uncomfortable with the billable losses in energy utilisation.

However, that still leaves the original question of legislation unanswered. Does this mean that when we buy a product that states "50W" we should not rely on that when we calculate our power consumption? Isn't there a regulatory body through which all electrical goods must gain approval before they are committed to the market? And if there is, what rules must the manufacturer / distributor / wholesaler abide by, at least in terms of claims about power utilisation / power output? Or is that a cross-over between a regulatory authority for energy and the Fair Trading Department?

Somehow, I'm starting to feel more comfortable with my no-name, Chinese made, low-cost items. Sadly.

Cheers - OziOscar.

[Markus13]

You must remember in relation to Aquarium equipment in Australia, only heaters must be approved (certified), anything else, well lets just say there is no legislation to stop items of the correct voltage being sold here (unless an ordered or voluntary recall has been issued)

[wui39]

Careful when you say efficient. What is there to say that the Eheim is not also 90% efficient? He only said that they had a power factor of 0.5. That does not make them inefficient with the 50 watts of real power used and charged for. What is to say that Chinese pumps are any better with their p.f. They won't tell you. You may have to measure it yourself to ensure that.

A power factor is only an indication of how inductive or capacitive a load is. Of course in large industrial applications, the power authorities mandate that your p.f. is maintained in the region of 0.9, so that the onus is on you to ensure that the grid is not affected by large amounts of leading or lagging current.

In regards to large pumps and or motors, in light of the power authority’s view, they are designed to operate with a power factor 0.9 with corrections. Pumps and motors that are a fraction of a horsepower are inherently more difficult to get a high p.f.

Another case in point, many large building as well as homes now use fluros for light. Fluro lights have a power factor of 0.6. In large building they are forced to correct this so that their p.f. is 0.9-0.95. At home your fluro is not corrected. An incandescent lamp has an almost unity p.f. So your fluro light consumes 11 watts or 18watts with its reactive load. An incandescent consumes 45 watts in total. Are we still using less power?

As already agreed earlier by the starter of this thread, the measurement he took may not be entirely accurate due to the equipment used hence the quoted figure of 96 watts may or may not be accurate.

[Pacco]

"The real simple answer is that Eheim quote all power consumption as True Power because this is what your electricity supply company charges you for and it is what you as a consumer are generally interested in “how much will this equipment cost me to run over a given period”. "

That is a real simple answer

Personally, I would still even buy the Eheim even if it was using twice the wattage for the simple fact they are one of the most reliable submersible pumps you can get. I know if I buy one I am very likely to get more than 10 years of consistent high quality performance from it, even if I don't maintain it regularly. I would prefer to pay a little extra "insurance" against fish losses from equipment failure. Until someone tests a few units with an actual power usage meter I will trust 50W on the box rather than 0.4A on a tong.

Cheers

Pacco

[mianos]

Dan's Data Dan has an another quite good introduction on power factor :

http://www.dansdata.com/gz028.htm

The key point is, as Dan points out, if you put the object in a closed box the real power used is the energy generated and lost as heat or other radiation. This is significant also for tanks as the water cools the motor.

(and as wui39 points out for the power companies if you have lots of motors or non unity PF equipment)

[Tas_Dean]

This is a bit of a grave dig, but as I have an electrical background I thought I might add my take.

I read this thread from the start, and right through, i was thinking "this guy has used a clamp meter, which on ac equipment measure CURRENT DRAW (amps), not POWER (watts)". And the email from eheim has confirmed exactly that. It is also true that most Tongue testers (also known as current clamps) are not very accurate at such a low current. However, in this case, it appears that the current clamp that was used is quite accurate.

Power companies in Australia charge domestic users, and most small businesses for POWER (Watts x Amps x Power Factor), not current (Amps).

Where I used to work (one of the biggest power users in this state), we were charged for the current we used. Therefore, we ran a lot of power factor correction devices in order to get our current down. For a simple explanation of why, if all our devices had a power factor of .5, then we would be paying twice as much per month than we had to with our PF corrected. When the power bill was in the $MILLIONS per month, this could quickly make a large difference.

Do not confuse Power Factor with Efficiency. At a rough guess, I'd say that the motor is about 70% Efficient. This would be a fairly typical efficiency value for a motor of this type. For an electric motor to have an efficiency above 85% is unusual. Above 90%, almost unheard of!

Power Factor is an extremely hard concept to grasp, but all you need to be concerned in (as far as your power bill anyway) is the rated input power. This is what you pay for, as it is what your power meter measures.

If concerned about overloading circuits, then you need to calculate the full load current.

In relation to voltage: Australia's legal supply voltage is 230 Volts, and has been since 2000 (or maybe 2001). However the legally allowed tolerance is +or- 10%. This means that your voltage supplied can legally be between 207 and 253 volts. This change was made largely to fall in line with the European Union (220V), and to reduce the peak allowable voltage under 260V (the reasons for this are more in depth). In practice, most people will still see somewhere close to 240V at their outlets.

DISCLAIMER: I have not posted this in support of EHEIM. I have no EHEIM equipment, and no commercial interest in any aquarium products.

HTH

Cheers, Dean

[fw05racer]

Wow such a long post....thanks for al the info guys.

Um Dean I think your post was really just a summary of what everyone else has already said.

I've heard that voltage is still at 240V because no one at the electrical authority has been bothered to change the taps on the transformers.