I understand that a meter needs an "inrush current" capability that most meters don't have. The reason being that the inrush current only lasts 3 or 4 cycles (10ms) and goes by too quickly for regular meters to measure. If you put the meter on "max" you are measuring current draw not only on the first 10 ms of inrush, but also on the next 990ms of startup current which is less current draw as the motor gets to full speed and therefore a lower reading than the inrush current value as the two are combined over the 1 second start up. I just installed a new 3 ton condenser, coil, and furnace with a LRA of 77 and I measure 85 amps of inrush consistently using the inrush capability of my meter.

@ianrosal1235

5 ай бұрын

buy UNI-T 208b it has inrush current😊

Thanks for the info!

This is not an accurate way to measure inrush current. You need a clamp meter with an Inrush button on it that is specifically designed to measure Inrush current which occurs during the first 100 ms of startup. I’ve tested this on my compressor with a Klein CL900 that has both and Inrush button and a Max/Min button. Consistently, I get a reading of 98A for Inrush and for MAX, I get a reading of 76A. It’s not the same thing.

New subscriber here. As a home owner I am trying to add up all my inductive loads for the house and am measuring surge or startup current on the heavy hitters such as my HVAC, Well Pump, and machine tools such as table saw and welder. Thanks again for your video.

Quite incredible 10x the avg current

66 is close to 82?

Great video helpful

Fantastic✔Sent this to my HVAC folks since they didn’t know how to use their clamp on meter etc. I want to run my AC on a portable generator so need the new surge amps after the soft start installation. If it’s below 30 amps, I’m good.

It may be beneficial to inform folks about the difference between a hard start kit and a soft start kit. A hard start kit actually will not change the inrush current, it will simply decrease the duration of this spike. A soft-start kit, on the other hand, should decrease that spike peak.

Awesome video, very clear, visually and technically. Thank You!

I like to see the compressor at 75% of the RLA rating. I take running conditions and refrigerant charge into consideration when checking amps to deciding the health on the compressor I’m working on because amps will fluctuate in different situations

@johnconnor7501

Жыл бұрын

I agree

I'm confused! As the inrush current goes down, that's a problem? I would think as long as the inrush current is less than LRA that would be a good thing. Less current, less heat. No?

If inrush measures the maximum current drawn by the compressor, what does the MAX button on the meter do? Thanks.

@JPTinioMedia

4 жыл бұрын

The max button could do it but its not accurate as the max button isn't fast enough to measure the inrush amps which is why newer or fancier meters have a dedicated inrush

@dantronics1682

Жыл бұрын

The max button stores the max current or voltage measure by the meter in the timeframe that you are measuring, it doesnt measure the inrush current since its an average. If you was to use a storage scope on motor switch on you would see a massive spike, thats the inrush currrent of v/r when there is no back emf

Are all inrush clamp meters huge?

what model number fluke meter you are using?

@qiangzheng821

3 жыл бұрын

Fluke 902 FC True RMS HVAC Clamp Meter

I am wondering which breaker you were using for this 66 Amp ?

@james10739

3 жыл бұрын

I mean probably just whatever it's calling for like a 20 or 30 since it only pulls like 6 while running I assume there is also the fan but a breaker can handle it for this couple milliseconds

@Adrianyoutubing

3 жыл бұрын

My guess, here in the UK a 20A type C or D type MCB.

The problem with trying to diagnose using Inrush Amperage measurements is and I'll quote Fluke Instruments "Inrush amperage can be 4x to 10x RLA" so with out a substrate or baseline amperage, you can't judge wear and tear.

@JPTinioMedia

4 жыл бұрын

The LRA number is what the engineers have designed for that specific unit to pull when the unit is locked or trying to start up, if your inrush is below that number its using less to start up, if you ever come across seized motors the amp draw is usually a lot higher and stuck at the LRA rating if the motor has an lra rating. From what I was told and taught at least

Show the difference with a hard start.

@dantronics1682

Жыл бұрын

I heard him saying hard start but I thought it was soft start

Does this meter have DC my... yes,no.....¿¿

Mine just says OL, ALWAYS doesn't matter which wire I put it at, it's annoying

@dantronics1682

Жыл бұрын

thats what it should do, ol means over load. thats why you need a meter with inrush current reading

What model fluke meter is that?

@b-2466

5 ай бұрын

Looks life 902fc which is what I use and it does not measure inrush current.

RLA = Rated Load Amps. Measured amps while compressor is running. LRA = Locked Rotor Amps. A locked rotor is the worst possible case for impedance that leads to the highest measured amp reading.

@deang5622

Жыл бұрын

Incorrect. Impedance doesn't change. It's a function of design of the motor. What changes is the magnitude of the back EMF. When the motor is not rotating, there is no back EMF, and the circuit is simply the DC resistance of the coils and the voltage across them. The coil resistance is low and hence the locked current is high I am surprised how many people are making statements on how motors operate and do not understand basic motor theory. It's shocking

@juanitaharris4320

8 ай бұрын

SHOCKING indeed :)@@deang5622

This video is absolutely misleading. Inrush current measurement can only be performed using meters that have an inrush capability and equipped with inrush button. This guy did the test with the tool, which does not have an inrush option and not measured correctly.

@PH-md8xp

Жыл бұрын

That is correct. Using the Max button is not the same thing as Inrush.

Missing the most important piece of info "which wire are you clamping your meter to?" Thanks!

@joshflynn9388

5 жыл бұрын

Common

@Editronone

3 жыл бұрын

Not trying to be mean, but if you don't know what wire it goes on don't even take the cover off.

@PH-md8xp

Жыл бұрын

@@Editronone Lots of people are learning here, there are no bad questions. Better to ask and gain knowledge than not to.

Can it measure Inrush DC ?

The reason why I viewed the video is to see what wire you're measuring for inrush amps. The video had no information

I bet the in rush current on a new unit is probably real close to 3X the running amps

@UnbornWarrior123

3 жыл бұрын

Hi, I am also surprised to see the inrush currents are 10 times the steady state currents and he is counter verifying with the name plate details.

@dantronics1682

Жыл бұрын

it can be up to 50 * running amps but last only 0.5 seconds which is why the fuse doesnt blow, most fuses are antisurge.

Yea max is similar but not inrush. Inrush is a spike, max is over a duration

Too much guessing for an educational video

@hounddoggzgaming6970

6 жыл бұрын

Armand Melch its called a system diagnostic real tech have to test multiple components before we replace a part. We call this trouble shooting i know this is brand new to you.

@ameen3372

4 жыл бұрын

yes, indeed

You are not measuring an inrush current .