High Peak Currents

[martinh287]

Hi

Had a data logger installed on the mains supply of one of remote buildings on the site to see if their is enough capacity in the supply to allow for the addition of 103 additional double sockets.

The data logger was installed on the mains incoming to the building for 3 days and the logger was logging the min, Maximum and average over the 4 minute period. the information suggests that we have a electrical load creating high inrush currents as the maximums over certain periods were 450 amps to 540 amps and the minimums (Around 50a) and averages (75a). However before we pinpoint the electrical load in question and look at the possibility of inrush current limiters was after some advice on inrush currents.

Has anyone got any relevant information on inrush currents, Wanting to know when is a inrush current 'excessive' so can make a judgement of the severity, If any of the issue.

Thanks in advance guys

 

[matthunt]

Hi Martin,

Do you have a snapshot of the maximum inrush period, you should be able to grab this from the logger report, also what the voltage is dropping to over this period, are there any large transformers down line ?

 

[martinh287]

Hope you can see the image clear enough. This a screen shot of a section of the graph we received with the data logger info. The higher currents are maximums of each phase the linesame at the bottom of the current scale are the averages tried to upload a image of the excel file but can't get it to show the titles at the top so you can understand what the numbers are representing

We have a mammagraphy scanner connected to this supply which is were we believe the inrush currents are coming from. The data logger information on voltage sent back to us is shown below

 

[martinh287]

Just a update. Installing the data logger onto individual db boards next week

 

[Darkwood]

What does the industrial premises contain, what kind of machinery, lighting etc, what is the starting nature of said machinery and the Duty (no' starts per hour?)
Your graph shows peaks but the time line is missing so hard to intrepret.

 

[martinh287]

Hi. The building utilisation is mostly office areas currently occupied by around 20 staff has 1 single phase lift hydraulic lift, gas heating, 2 industrial washing machines and one industrial dryer. Pump sets are around 3.5kw three phase. There is a external mammagraphy unit using our electric supply. Because it is service and ran by a different company. All we know at this point is it is required to have a 63a three phase supply. The question has been raised for more information

The graph was what was received back from the hire company that hired the data logger. Won't be able to put a time scale on until back in office. The peaks are basically between 08.00 and 17.00 and graph shows the information over the three day duration.

 

[Darkwood]

Still hard to interpret the graph as we have several different coloured lines, as mentioned missing timescale which if you suggest its over 3days would read that the peaks and troughs are daynight usage cycles thus no inrush currents that you suggest... think before we speculate any further we need to see the graph complete with scale and key.

 

[martinh287]

I will get scaled graph uploaded when I get it available to me. All can tell you for now is the the colour legendscheme for the graph. The graph shows the reading over each four minute log. What I pick up from the graph is that there is a couple of hundred amps between the min and max in the 4 minute periods which happens consistently thought out the day.

purple is imax for l1
Blue is I max for L2
Light green is I max for l3
Red is I min for L1
Brown is I min for l2
Green is I min for l3

 

[martinh287]

I have looked to put in the times for the graph however because there is over 1100 results at 4 minute intervals trying to install timescale onto the graph, it just doesn't work. i have took a image of some of the information contained within the excel file which i believe shows better what i am looking at.