Any EE's out there? Power questions..

byke

byke

Well-known member
I have a three phase 240vac motor that runs at about 6.5a, but pulls around 30-40a on startup. What I need to do is get that startup current way down, maybe half or better, so I'm looking at a soft starter because I want cheap and simple with three little dials and that's it, no VFD. I found one that looks promising(SR22-16), but what I'm mostly wondering about are the tools necessary to capture the startup current so I can see the changes being made at the soft starter. Diving into the world of power quality analyzers and dataloggers has my head spinning. What are some affordable ways of getting snapshots of the startup profile?
 
byke

byke

Well-known member
All I need is to see is the startup curve until it settles, which normally takes maybe two seconds tops, but maybe a little longer if using a soft start? Either way, not very long. I have limited experience here, but I recall the triggering being an issue when you want to look at something happening fast, so I was worried I'd be looking at big bucks, plus three phase tends to complicate things. I'd like some sort of graph in whatever file format I could save/view on a pc. I'll check out the 434/323.
 
M

motomania2007

TC/MSF/CMSP/ Instructor
byke said:
^^^That's why I always go New Balance, good for wider feet.



I'm an auto-set kinda guy, but I suppose I could figure it out. Just a four channel something or other and a few amp clamps?

https://www.amazon.com/Rigol-DS1054Z-Digital-Oscilloscopes-Bandwidth/dp/B012938E76

https://www.amazon.com/Hantek-CC650-Current-Clamp-Oscilloscopes/dp/B009R15SJG
Click to expand...

There are pretty cheap, portable o'scope type meters out there.

I expect there are some barfers that have them. I know there are some barfers that are industrial electricians and they should be able to handle this.
 
Cycle61

Cycle61

What the shit is this...
If you just want to capture the peak ampacity numbers, the cheap meter mentioned above will do it. It will save maximum in rush current readings and such. Only one phase at a time though. If you want a snazzy graph of three phase current readings plotted over time, you're definitely going to be spending a few more dollars for the machine, even is a rental.
 
ctwo

ctwo

Merely Rhetorical
I have that Rigol DS1054Z scope. If you do end up getting that it is the absolute best deal. It is amazing for the money and I would buy it again, unless I was gonna spring for thousands more.

There are some logging clamp meters that can interface with a PC. I would probably build my own inductive pickup and log with an Arduino microcontroller. I want to do that anyway for my CNC mill, so maybe I'll try something this weekend. Could be a $5 solution.
 
afm199

afm199

Well-known member
byke said:
I have a three phase 240vac motor that runs at about 6.5a, but pulls around 30-40a on startup. What I need to do is get that startup current way down, maybe half or better, so I'm looking at a soft starter because I want cheap and simple with three little dials and that's it, no VFD. I found one that looks promising(SR22-16), but what I'm mostly wondering about are the tools necessary to capture the startup current so I can see the changes being made at the soft starter. Diving into the world of power quality analyzers and dataloggers has my head spinning. What are some affordable ways of getting snapshots of the startup profile?
Click to expand...

How old is your circuit breaker panel? The older ones (sixties and seventies) had pre-HACR breakers and didn't withstand inrush current well. A HACR rated breaker is designed to withstand high inrush current for a long enough period to get a motor going. Newer breakers meet the standard. If your breakers are from the sixties or seventies, try swapping out the breaker with either a modern breaker ( anything after 2005 or so) or an older breaker that has "HACR" printed on the front label.
 
byke

byke

Well-known member
Cycle61 said:
If you just want to capture the peak ampacity numbers, the cheap meter mentioned above will do it. It will save maximum in rush current readings and such. Only one phase at a time though. If you want a snazzy graph of three phase current readings plotted over time, you're definitely going to be spending a few more dollars for the machine, even is a rental.
Click to expand...

I'd really like to be able to see the curve so I know what's happening and for how long. I have a fluke amp clamp and I think it can be set to record peak and that's definitely useful, but being able to see amplitude/time is the goal.

ctwo said:
I have that Rigol DS1054Z scope. If you do end up getting that it is the absolute best deal. It is amazing for the money and I would buy it again, unless I was gonna spring for thousands more.

There are some logging clamp meters that can interface with a PC. I would probably build my own inductive pickup and log with an Arduino microcontroller. I want to do that anyway for my CNC mill, so maybe I'll try something this weekend. Could be a $5 solution.
Click to expand...

Yeah that Rigol gets good reviews. Crazy how cheap a decent they are.

ctwo said:
Surely, it's already been done...

https://olimex.wordpress.com/2015/09/29/energy-monitoring-with-arduino-and-current-clamp-sensor/

https://create.arduino.cc/projecthub/achraf-oukheir/current-sensor-ac-085187
Click to expand...

This would be a fun project I'd seriously consider if the the programming for three inputs over a pretty graph were already done.

afm199 said:
How old is your circuit breaker panel? The older ones (sixties and seventies) had pre-HACR breakers and didn't withstand inrush current well. A HACR rated breaker is designed to withstand high inrush current for a long enough period to get a motor going. Newer breakers meet the standard. If your breakers are from the sixties or seventies, try swapping out the breaker with either a modern breaker ( anything after 2005 or so) or an older breaker that has "HACR" printed on the front label.
Click to expand...

Everything is from at least 2004 and I was thinking of trying to power the motor with a rotary phase converter, but otherwise it's just through a generator.
 
wazzuFreddo

wazzuFreddo

WuTang is 4 the children
I wish I had gotten the chance to snag the Hioki power meter we got in the Clipper Windpower bankruptcy before it got lost in the SunEdison bankruptcy :p

The triggering sucked on it though.
 
ctwo

ctwo

Merely Rhetorical
byke said:
I'd really like to be able to see the curve so I know what's happening and for how long. I have a fluke amp clamp and I think it can be set to record peak and that's definitely useful, but being able to see amplitude/time is the goal.



Yeah that Rigol gets good reviews. Crazy how cheap a decent they are.



This would be a fun project I'd seriously consider if the the programming for three inputs over a pretty graph were already done.



Everything is from at least 2004 and I was thinking of trying to power the motor with a rotary phase converter, but otherwise it's just through a generator.
Click to expand...

I used Processing a while back to get live plots. Then I used PuTTy to log a data file read by Excel, which will automatically update at intervals. For my solar panel, I log voltage and current to an SD card and read that periodically.

There's always the old fashioned way too, with like a pencil and French curves :afm199
 
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