Suppressing surges

[shermans]

I have a 220 volt, 20 amp change-over interface relay switch which sometimes causes a surge when the coil is activated. When this happens, it wipes the memory of a digital time-clock on the same circuit. I want to suppress the surge by absorbing it in a diode. The actual current draw though the relay switch is less than 3 amps.

Can anyone tell me what sort of diode I need to achieve this ? I imagine that the leads from each side of the diode would be connected to the positive and neutral terminals of the relay switch, but I do not know what to ask for in the component shop ! I have searched the index for diodes but there are thousands of them ! What should I look for ?

Thanks for any advice.

 

[shermans]

Thanks for this info. I have downloaded the speification, but to be honest, I am lost ! What do I do with this ? The relay switches on a 220 volt central heating boiler / furnace. The digital time-clock is between the distribution board with the 220 volt relay and the boiler / furnace and simply controls the circulating pump after the relay has been activated to switch on the boiler / furnace. The problem is that the time-clock's memory keeps getting wiped from time to time by the operation of the relay switch. If I substitute it with an analogue time-clock, there is no problem.

The relay switch is activated by a dtmf signaller which enables me to turn on the central heating remotely in the winter by phone; to save fuel, the building is not heated except in freezing weather and there are often several weeks between visits - a simple telephone call therefore turns it on, after which it is supposed to be controlled by the time-clock. But if the time-clock's memory gets wiped, then it either stays on permanently or does not come on at all. There is a battery back-up for the time-clock which means it keeps time when the power has been removed by the dtmf signal; that is why I cannot use an analogue time-ckock which would not suffer from spikes.

I was hoping to find a simple solution by being able to install something like a diode across the two switched terminals of the relay switch, whereas the TPS54425 seems to be unsuitable for 220 volts and requires installing on a board. I have found out where to source a TPS54425 but I honestly do not know what to do with it !

Thanks nevertheless.

 

[CocaCola]

Who are you talking to?

Are you another one of those that is cross posting yourself to multiple forums, making for broken threads with only half content?

 

[shermans]

Hi Coca Cola

Sorry about that. I was replying to what I thought was an answer to my question but I am embarrassed to realise that my reply was to an advertisement in the line above. The product advertised appeared to be an answer to my question, and now I feel so dumb !

I can promise you that I am not cross-posting !

 

[CocaCola]

OK, I can understand that, jumped the gun a little as we just had some guy cross posting to multiple forums and it resulted in a broken thread...

As for your issue, it's really hard to figure out what is resetting the timer... But, have you tried an over the counter surge suppressor on the supply side? It might be that the supply (mains wiring) is surging with the on/off cycle and is simply causing a slight 'brown out' that resets the timer...

 

[cjdelphi]

Suppressing Urges did you say?.. Medication talk to your doctor