[Prev][Next][Index][Thread]
Re: 50%
In a message dated 96-11-11 00:58:23 EST, Malcom writes:
<< By "dwell" as applied to a rotary gap I mean contact closure time
(gap fire time). I realize that is counter to the automobile
definition.
>>
The definition of "dwell" as applied to the Tesla coils gap and the notion of
"dwell" as it applies to automotive function is actually very similar (if you
confine the discussion to rotary gaps). The McGraw Hill Dictionary of
Scientific and Technical Terms (1994) defines automotive "dwell" as :
---------
The number of degrees through which the distributor cam (rotor) rotates from
the time that the contact points close to the time that they open.
---------
This definition indicates that in a situation in which the "dwell" (also
called the "dwell angle") is large, the *time* during which the contacts are
closed (current flows) is also greater, where when the "dwell angle" is
small, the *time* of contact closure and current flow is less.
The bottom line in both cases, seems to me, is a description of how long the
contact is closed and the current flows, although in the case of the rotary
gap, the problem of "arc over" may occur in which the length of time that
current flows may greatly exceed the time during which the "contacts" are
actually closed. This effect can, I understand, be minimized by proper (and
rather sophisticated) design of the rotary gap with some form of
"alternating" contact geometry....see Richard Hull or Bert.