Is a switch available that will sense a 240V supply (to a fan) has been
switched and then itself switch a separate 240V supply (to a 230W
resistance heater) for 15 minutes and then switch off and not reset until
the original supply to the fan is off again?

AJH

andrew wrote:
Is a switch available that will sense a 240V supply (to a fan) has been
switched and then itself switch a separate 240V supply (to a 230W
resistance heater) for 15 minutes and then switch off and not reset until
the original supply to the fan is off again?

AJH
Possible not a switch in the sense of something you mount on the wall
but there will be relay based modules that should do it but normally
from the same supply.
An industrial time delay relay will be expensive but likely to have more
options such as separate sensing and load circuits

Look at RS, Farnell and maybe CPC

Bob

In article ,
andrew writes:
Is a switch available that will sense a 240V supply (to a fan) has been
switched and then itself switch a separate 240V supply (to a 230W
resistance heater) for 15 minutes and then switch off and not reset until
the original supply to the fan is off again?

The logic circuit is called a non-retriggerable one-shot or
non-retriggerable monostable.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On Sat, 10 Apr 2010 10:05:35 +0100, andrew
wrote:


Is a switch available that will sense a 240V supply (to a fan) has been
switched and then itself switch a separate 240V supply (to a 230W
resistance heater) for 15 minutes and then switch off and not reset until
the original supply to the fan is off again?

Crouzet Chronos 2. You need "function H" which is timing on
energisation.

http://www.edcscotland.co.uk/acatalog/EDC_Products_Electronic_Timers_214.html

has the MUR1 at about a third of the usual price and also the MBR
described as single shot. They also look as if they could answer
questions on it!

MUR 1 Data sheet
http://www.crouzet.com/english/products/micro-control/din-rail-mounted-electronic-timers/chronos-2-timers/88826105-17-5-mm-din-rail-mounting-mur1.htm

Peter Parry wrote:

On Sat, 10 Apr 2010 10:05:35 +0100, andrew
wrote:


Is a switch available that will sense a 240V supply (to a fan) has been
switched and then itself switch a separate 240V supply (to a 230W
resistance heater) for 15 minutes and then switch off and not reset until
the original supply to the fan is off again?

Crouzet Chronos 2. You need "function H" which is timing on
energisation.


I searched on the terms Andrew G gave and only found 12V circuits, your off
the shelf 240V one fits the bill so I have ordered this and a 240V relay to
strap across the fan terminals.

Thanks Peter I would normally have 'phoned after posting here first to give
the others a chance :-)

AJH