R
Ross Herbert
Guest
On Sat, 31 Jan 2009 01:37:13 GMT, Ross Herbert <rherber1@bigpond.net.au> wrote:
:On Sat, 31 Jan 2009 00:23:24 GMT, Ross Herbert <rherber1@bigpond.net.au> wrote:
:
:It occurred to me that you could also try connecting both relay contacts in
:series to increase the effective contact gap at opening which is where the
:majority of arcing will occur.
:
:A search of literature on arc suppression capacitors for a load such as yours
:indicates that a value of about 13uF would be required. Since it would need to
:have a rating of 300Vac this would make it bigger than the relay itself so it
is
:not really a goer in my opinion. The cap could remain charged to line potential
:so that when the contacts closed again it would cause a high discharge current
:which would result in an arc of its own. A series resistor of say 5 - 10
hms/10W would need to be included in series with the cap to limit this
:discharge current.
:
:A search of patents revealed a fairly novel approach using a thyristor in
:conjunction with a standard relay to suppress arcing. Note, you may have to
:create a free account to view.
:http://www.freepatentsonline.com/3555353.html
Looking at the circuit, the thyristor idea might be able to suppress arcing
during closing of the relay contact but it would not do so when opening.
:On Sat, 31 Jan 2009 00:23:24 GMT, Ross Herbert <rherber1@bigpond.net.au> wrote:
:
:It occurred to me that you could also try connecting both relay contacts in
:series to increase the effective contact gap at opening which is where the
:majority of arcing will occur.
:
:A search of literature on arc suppression capacitors for a load such as yours
:indicates that a value of about 13uF would be required. Since it would need to
:have a rating of 300Vac this would make it bigger than the relay itself so it
is
:not really a goer in my opinion. The cap could remain charged to line potential
:so that when the contacts closed again it would cause a high discharge current
:which would result in an arc of its own. A series resistor of say 5 - 10
:discharge current.
:
:A search of patents revealed a fairly novel approach using a thyristor in
:conjunction with a standard relay to suppress arcing. Note, you may have to
:create a free account to view.
:http://www.freepatentsonline.com/3555353.html
Looking at the circuit, the thyristor idea might be able to suppress arcing
during closing of the relay contact but it would not do so when opening.