32 replies to this topic

[Homersimpson]

All I am saying is that if the maximum load is 3kw that is fixed, the variables are voltage and load (Amps), if the supply voltage drops and the load 3kw stays the same the Amps will increase.

Manufacturers will state the maximum load at a given voltage as below

Technical specification

Air Tank Volume 100 Litres Air Displacement 14.5 cfm Max Working Pressure 116 8 psi/bar Oil/Oil Free Oil Motor (HP) 3.0 HP Input Voltage 230 V Watts 2200 W Wheel Mounted Yes

 

We may have to agree to disagree on this ?

Hi, thats not correct i'm afraid, as above the only constant is resistance (or as correctly stated above impedance but lets not overcomplicate the problem).  The resistance is constant and as the voltage reduces so does the current and also crutially the amount of work done.

 

As an example we have an experiement at work with two 36kW three phase heaters, I had the supplies installed but it wouldn't reach the correct temperature.  When I went over and looked at the heaters that had been purchased by the faculty they were 480v not 400v and this small diference in voltage reduced their output to around 25kW each.

 

As these were the only suitable heaters available (and we already had them) I put a 400 -480V step up transformer on them and it fixed the problem.

 

If you want to understand more about this look up voltage otimising transformers like the PowerPerfector, basically these save energy by reducing the voltage and hence the amount of work done by all electrical equipment connected with a fixed output (i.e. a light), anything with a variable output (like a kettle, oven etc.) where the work done is regulated by a control will save nothing.  These only work on older buildings/equipment as more and more modern systems have a variable/regulated output.

[JXC Mini GT]

I have worked in the electrical industry for over 40 years and I fully understand voltage optimisers and have fitted power perfector equipment in a number of installations. 

My last word on the subject is this article from a compressor manufacturer,

 

Fuses Fail to Last

When compressor fuses repeatedly fail to last through their expected lifespan, it’s generally a problem with fuse size or voltage. In some cases, there could also be an issue with the unloader, valve or belts. Check for the following problems if fuse failure has been your constant burden:

• Incorrect fuse size — If a fuse doesn’t have the right ampere rating for the compressor, you could end up with a blown fuse on your hands. Always check the rating when purchasing subsequent fuses.
• Low voltage — If the voltage is improper, a fuse could receive the wrong amount of power. Check the voltage requirements and raise the level accordingly.
• Faulty unloader — Constant fuse failure could be down to an unloader that’s due for replacement.
• Defective check valve — Just as with an unloader, the check valve might be expired and therefore a problem for any given fuse if not replaced.
• Overly tight belt — With constantly blown fuses, it’s sometimes a matter of belts that are too tight. Check the belt tension and loosen if needed.

A fuse shouldn’t blow on any compressor in which the mechanisms are properly aligned. Even with a verifiably correct fuse size and voltage amount, you should still perform periodic checkups on the unloader, check valve and belts to ensure that problems don’t emerge that could impact the life of a given fuse.

[sonikk4]

Not all compressors have drive belts. The unit in question Is a direct drive from the electric motor to the compressor. My first one when brand new blew the 13 Amp fuse and several more. Hence why I said in one of my earlier posts I talked directly to the Technical department and they said about the plug not being correct.

The fact they are still selling these units like this smacks of either a company who refuses to supply the correct information or an inherent fault within the units themselves.

I’m afraid this is an argument none of us will win.