I've got 2 toroid transformers (Noratel model TA160/30) that humm significantly when I use a 40ah SSR to switch the 230v on.
Anyone know why this happens and if there is anything can do to fix it?
Anyone know why this happens and if there is anything can do to fix it?
The SSR probably uses a triac as switching element that will switch on once the voltage across the terminals has reached a certain voltage (I'd guess around 10-30V). This provides the voltage needed to operate the SSR circuitry on the switching side. And it also cuts off the first few percent of every sine (half)wave which leads to a current spike through the trafo at triac turn on time. From my POV there's little to nothing you can do about that except use a mechanical relay.
Yes, the ones I have use traics and I started looking for mosfet SSR's but they seemed harder to find and more expensive.
I am building a soft start as well and consider using the triac ssr for the NTC soft start and then shorting the SSR/mains feed with a mechanical relay.
This should bypass the triac issue (even though there may be a bit of humming at the start). Not sure though if the SSR will be "unhappy" being shorted?
I am building a soft start as well and consider using the triac ssr for the NTC soft start and then shorting the SSR/mains feed with a mechanical relay.
This should bypass the triac issue (even though there may be a bit of humming at the start). Not sure though if the SSR will be "unhappy" being shorted?
Mark Johnson made a soft start board for people: PCB: low voltage On-Off switch drives AC mains relay \ includes soft start .. H9KPXG