Now you can prevent contactor chatter or Brown-outs when
starting large loads or motors DOL. It is vital to know
exactly what the secondary voltage drops down to under these
conditions, although brief in nature they nonetheless pose a
serious cause for concern particularly if contactor chatter or
even brown-outs are to be avoided. These conditions can easily
draw current well in excess of the transformer full load
current rating.
Transformers can take a degree of overload under this
condition and although they may not be damaged, the secondary
voltage will decay away and we need to know just what that
secondary voltage will decay to. The dangers arise from the
risk of contactor chatter, even though this may be brief, the
contactors can become damaged, or they may hold very lightly
and could well exceed the thermal rating of the contacts in
the contactor. This condition could become a very expensive
hobby!
Now you can find the secondary voltage for all load
conditions.
To use this program, simply input the transformer data from
the manufacturer’s data sheet into the program and enter the
load value (either in Amps or KVA), press CALCULATE and the
program instantly displays the secondary voltage. Once known,
it is a relatively easy matter to contact the contactor
manufacturer and ask the “hold on” value for that particular
contactor.
“What if’s” are as simple as pressing the NEXT button and
entering another value!
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