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Siemens Thyristor SPNO 3RF23101AA02 shorted

applecruncher1

Jun 19, 2018
2
Joined
Jun 19, 2018
Messages
2
Hi,

We have a jacketed tank with a heating element (220 VAC, 650W) that is connected to a Siemens Thyristor SPNO 3RF23101AA02 as shown in the picture below. Our tank has a "Day", "Night", and "Off" options that can be controlled with a SP3T switch that determines whether to heat the tank to 45C, 31C, or no heating at all respectively. My problem is that the leads (1 and 2) of the Siemens Thryistor are normally closed even when its switch supply (A1 and A2) is not energized. Because of this, even when the SP3T is set to "Off" option, the heater is turned on.

F4674740-01.jpg


This is how it looks like with the front cover removed:
upload_2018-6-19_20-44-36.png

Removing the pcb, I think underneath is some sort of a circuit inside a silicon gel. I tested the leads 1 and 2 and they are shorted. Sorry I do not know what I'm seeing below as I have a limited knowledge in electronics. Is this supposed to happen? The Siemens Thyristor is an NO contactor so there should no connection from Lead 1 to Lead 2 in the first place. What could be the cause of this?

upload_2018-6-19_20-39-3.png

Thanks,
 

kellys_eye

Jun 25, 2010
6,514
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Jun 25, 2010
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6,514
We have a jacketed tank with a heating element (220 VAC, 650W)
Seems a bit 'low'.....

either way, the module is good for 10A (2.5kW) but devices do fail occasionally. Simple one-for-one replacement is required. Don't buy it direct from China though........
 

applecruncher1

Jun 19, 2018
2
Joined
Jun 19, 2018
Messages
2
Thanks for the advice. Do you know what's inside the silicone gel? Are those jumpers? It's my first time encountering an SSR contactor.
 

Harald Kapp

Moderator
Moderator
Nov 17, 2011
13,760
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Nov 17, 2011
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The photo is a bit blurry there. Looks like these are the actual thyristor dies with bonding wires (lots in parallel for high current carrying capacity).
 
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