Inverter Chatters

SCVJeff wrote:
There is likely nothing wrong with it except the transformer windings chatter when you start to pull a load. Unless you have the correct varnish and a little transformer savvy, either live with it or exchange it. It can be irritating...

Those HF (and pretty much all of the cheapo inverters and even PSW inverters) now days use the same setup as switching power supplies. They employ a HIGH FREQUENCY "CHOPPER" AT THE DC INPUT of the inverter.

They DO NOT USE OR HAVE A 60HZ transformer in the output stage.

The chopper typically runs just above 20Khz and typically uses a very small high frequency transformer. You will not hear any "chatter" from the chopper transformer, perhaps a high pitched squeal.

The chopper takes 12V DC and boosts it to 150-170V DC then the output stage will then switch on/off at 60hz.

What the OP most likely is hearing is from the OUTPUT transistors vibrating at 60hz which are typically heatsinked to rather large heatsinks or even the case of the inverter.

Inverters employing high frequency choppers typically suffer from rather short times for surge current capacity, so short that very few manufacturers will state the surge TIME.

By the way, very FEW inverters now days employ the old school 60hz transformer.. The Tripplite PV series is really one of the few which are STILL being manufactured! The PV series is a heavy duty brute which IS designed from the ground up to power HEAVY INDUCTIVE AC loads (like AC motors and fridge compressors).

Expensive, yes! $120 for a HF 1500W vs Tripplite PV1250 at $280

Heavy, YES! 5lbs for a HF 1500W vs PV1250 at 25 lbs..

But money well spent if you really want a inverter which handles not 100% surge but 125% surges for not microseconds but up to 10 minutes.. Heck they can handle 100% surges for more than an hr (don't try that with a HF or any other inverter on the market)!

I bought a PV-1250 for my home fridge conversion and don't regret it..