Hi,
I'm presently testing a longitudinally annealed Metglas core, but something
seemed wrong. So I began testing the cores BH-curve characteristics. The results
revealed a flat core! Below is the email sent to Metglas engineer. Does anyone
see any error in my test?
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Hi Ron,
I have a technical question regarding a core I purchased. According to spec it
should be a longitudinally annealed uncut toroid core made of 2714A material.
The part # on the package is MP2510P4AS. Directly on the toroid core says
P4AS04LG. According the spec this core should be highly square, but according to
my tests it's flat.
Here's the testing procedure. I placed a primary and secondary (12 turns each)
on the toroid. The primary is connected to a small 100 KHz current source signal
at 20 uA AC p-p. On the secondary is a manually adjustable highly precision
current source that is slowly change (in ~2 minutes duration) back and forth
between +140 mA to -140 mA. I'm viewing the 100 KHz small signal directly across
the core, which represents the cores present permeability. What I'm seeing is a
core that gradually decreases in permeability between 0 and 140 mA. Furthermore
investigation shows the core has no appreciable hysteresis.
Could you please shed any light on this? Are those part numbers (MP2510P4AS,
P4AS04LG) a longitudinally annealed 2714A material? What are the odds of
Metglas sending me the wrong core?
Any help is greatly appreciated!
Kind regards,
Paul Lowrance
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