AC frequency is more than 800Hz

Yaakov

Joined Jan 27, 2019
3,523
Also, if you actually had such a situation, very few of your household appliances simply would work, if any at all, and things with motors like refrigerators and air conditioners would make it very clear they were unhappy, so absent screeching, fires, and failures—your meter is not working.
 

Yaakov

Joined Jan 27, 2019
3,523
I mesured 1 phase as 50Hz stable and 1 phase varying 50-800Hz.
There is no mechanism for your mains to have a frequency other that 50Hz with a < 1Hz variation. There is an absolute requirement the generators creating the power stay in the range and nothing between you and them that could shift ithe frequency.
 

wayneh

Joined Sep 9, 2010
17,153
High frequency noise on the line may be causing your bogus meter readings.
I highly doubt that.
What makes you think that's what caused the failure?
I read it as the pump is broken, so that's why he's probing around and seeing the odd frequency reading.

If the circuit has failed open, perhaps he's seeing an artifact such as EM from fluorescent lights.
 

strantor

Joined Oct 3, 2010
5,646
Your power comes from a rotating machine somewhere. That machine is spinning 3,000 RPM (maybe 1,500RPM) to deliver 50Hz. In order for it to deliver 800Hz, it would have to spin 16 times faster, 48,000RPM. Even if you receive power from a nuclear plant in runaway condition, I doubt it could spin that fast without flying apart. All the transformers on poles would be exploding around you. In other words, you are not receiving 800Hz power. Your meter is lying to you. They do that sometimes, especially the cheap/crappy ones.
 

Thread Starter

josepars

Joined Nov 28, 2018
73
I read it as the pump is broken, so that's why he's probing around and seeing the odd frequency reading.

If the circuit has failed open, perhaps he's seeing an artifact such as EM from fluorescent lights.
Pump broken, then I tried to investigate source of the problem I saw the frequency was unstable
 

andrewmm

Joined Feb 25, 2011
1,757
Thank you,
What I think is happening, is to do with the meter.
It looks a lovely meter,

but I wonder how it measures frequency ?

If the input was say a nice square wave, it could time between two rising edges, to give a frequency,
same would work for a nice sine wave, as in perfect AC mains.

BUT

The real AC mains, is going to have lots of spikes on it, like this,
1620289621471.png

now what is the meter to do ,
it measures between rising edges,
in this case its going to read 6 times the real frequency

what happens if it has two spikes, quiet close,
the it would measure these as the frequency , and could be very high.


You really need to look at the quality of the signal,
which is a scope job,
if its a nice sine wave, then the frequency meter is fine,
if it has spikes, then the frequency meter is not of much use.
 
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