Could just be a battery charger, or tester. There is a fuse (top left, big glass thing). I'm betting thats what it is.

Pretty sure it's a generator (predecessor to the alternator) tester. Most of what you see to the left (besides the glass fuse) is a coil which produces a load, to determine if the generator will work under pressure, rather than just at idle. Most likely home made.

I think it is a converter from car to house current is why it has a house views on

from this picture there are three items that can bee seen a relay a fuse and an ampmeter. the relay is all the stuff on the left hand side except the glass fuse. It works by having a small amount of electricity go into the wire coiled around an iron bar to create an electro magnet. that is the item that looks like it is wrapped in black plastic. This in turn will attract the iron bar that runs vertical on the far left to connect the contacts of the switch. The knobs are to adjust exactly how much electricity is required to move the switch. The fuse is just to prevent to much current from flowing through the item. But what gives it all away is that ampmeter on the right. Amperes is the unit in electricity that describes the amount flowing. The only ampmeters that have a scale as shown on this device are ones made to charge batteries and the way the meter works is when it is to the left or right of zero up to 15 amps that is the current flowing into the battery. The relay is used as a circuit breaker to turn off the charger if it is charging to fast. and the fuse is a last resort if the mechanical switching of the relay takes to much time. So in short the first guy nailed it. It is a Battery charger.

Holy crap John Doe - THANKS!!!!!!!!!!

It's a contactor used to switch large amounts of current. A small amount of current is applied to the electromagnet which closes the contacts to switch a large amount of current. It was likely used in a house or commercial building, probably as a motor starter. Tom

It's an industrial breaker. The fuse is a 1.5 amp rated fuse. The green paper was 1.5 amps, white paper for 1 amp, and red paper for 20 amps.