# At what input frequency of an LCR meter should I measure the inductance of a solenoid valve?

I wanted to measure the inductance of a solenoid valve that I have: Airtec 2P025-08. I took it to the university's electronic valve. There was an LCR meter and I measured this values:

1. @ 120hz : R = 33.6 Ω, C = -33.7 uf, L = 52.5 mH

2. @ 1000hz : R= 126.4 Ω, C= 4.458 uf, L = 15.93 mH

Which one should I use for a solenoid valve. The guy in charge of the lab told me that I should use those for 1000hz. I think he said 120 hz is for measuring inductance of motors (if I am not wrong).

I read this and it says use 200khz for measuring inductance: How to Measure Inductance

Which one should I use? If I should use those that belong to 200khz, how much are they different comparing to the values at 1000hz?

And one last question: if I want to simulate it with LTspice, Should I enter the values in the Solenoid block like this:

Or do I have to add a resistor and capacitor manually like this:

I am baffled... because I get different simulation results!

I am a beginner in electronics and LTspice,

Thanks :-)

I think that there is something wrong either with the LCR meter or with the way you used the meter.

It is extremely unusual to see significant capacitance on a solenoid valve. Let's call that indicator #1.

The resistance value should be the same no matter what frequency was used. This is assuming that the LCR meter measured the resistance at DC. Let's call that indicator #2.

What DC resistance did you measure with a DMM? If you haven't done that yet, please do so when you get a chance.

The datasheet says that the solenoid consumes 7.0 VA (AC) or 7.0 Watts (DC). That value and the DC resistance that you measure will let you figure out what voltage the solenoid needs if you don't already have that figure.

I normally measure inductance using a fast MOSFET and pulse generator. I simply monitor the current on a scope as I increase the pulse width. Given the DC voltage that I'm feeding into the coil and the slope of the trace on the scope (showing current), it's trivial to calculate the inductance.

• I knew something was wrong! Because with the multimeter I get 20.2 Ω !! The LCR meter didn't have any settings for changing the input to DC or AC. Is there any way to measure the corresponding DC values for LCR from these values that I have?! May 28, 2015 at 5:33
• For DC, both L and C are meaningless. C is just open, and L is just short-circuit. May 28, 2015 at 13:34