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# Re: some proposals for future developments

- To: femm@yahoogroups.com
- Subject: Re: some proposals for future developments
- From: "atreding" <atreding@gwlisk.com>
- Date: Mon, 29 Sep 2003 17:36:23 -0000
- In-reply-to: <5.1.0.14.0.20030929074503.00af2638@staff-mailin.lboro.ac.uk>
- User-agent: eGroups-EW/0.82

    We generally cycle the parts a few times before we test them, so they
    will be in the proper working condition when they are tested - that
    is, the state they will actually be used in. We do sometimes see
    differences in the forces between the first time we ever cycle them
    and subsequent cycles, but it is generally a pretty small contributor
    compared to other factors at work. We have tried this method in the
    past (approaching the target current from both directions) and we do
    see some difference, but not usually enough to be significant. Using
    an ac source to demagnetize the samples might be an interesting thing
    to try - although it won't be representative of the actual usage of
    the unit. Maybe I'll give it a try next time I run into the issue and
    see what happens. Thanks.
    Andy

    --- In femm@yahoogroups.com, Keith Gregory <k.gregory@l...> wrote:
    > I asked about the excitation because I was thinking about
    hysteresis; has
    > it been considered?
    >
    > Have you noticed any change in the force at low levels of
    excitation after
    > a solenoid has been driven to saturation?
    >
    > You could try demagnetizing a solenoid using a reducing ac
    excitation then
    > measuring the low level force with dc excitation that is only
    increasing.
    > Follow that by driving the solenoid into saturation and then
    measuring the
    > low level force with a deceasing excitation. If there is any
    difference
    > between the two measurements then hysteresis is affecting things.
    >
    > Keith.

- References:
  - Re: [femm] Re: some proposals for future developments
    - From: Keith Gregory <k.gregory@lboro.ac.uk>

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