This Whirlpool electric stove, model number RF0100, appears to be an older model. If you were wondering what blasted the ground lead of my Kill-A-Watt meter which I posted about two days ago in the thread about the Phillips security screw, this is the culprit. The schematic is here:
I used to have the stove hooked up to a 240 volt circuit as indicated in the schematic and it worked ok. But, now I don't have a 240V line. Or at least not yet. I was trying to at least get it to work on 120V because only the oven will be used and at very low heat, probably around 200 degrees to cook some ceramics. The stovetop and broiler wires have been disconnected because they are not needed. This particular model does not have a light or a clock as shown in the schematic. I wired it so that L1 went to hot (black), L2 went to N (white), and N to ground (green). The load across the electric plug, hot to neutral, with the oven switch on, is 17 ohms. That makes sense to me. However the impedance reading from neutral to ground makes no sense to me. I've tried two different dvm's and they both give bizarre results. When starting at the 2M ohm range, the meter starts at about 700k and counts down to about 300k and holds there. When I move the switch over to the 20M ohm range, the meter starts at about 2.3M ohm and counts up. The other meter which is a portable meter counts backward too and then the minus sign appears on the meter as if current is coming into the meter. From what I can see, there aren't any capacitors or semiconductors interfering. The oven thermostat has a thermocouple wired to it which for some reason is not shown in the schematic. I opened the thermostat and found an interesting mechanical coupling that moves a slider bar that depresses either the oven element switch, the broil element switch, or both. Then there is the thermocouple wire which is wrapped(?) internally around the rotating control that selects the oven temperature. I don't usually open oven thermostats so I'm not sure what exactly is going on inside because once you open the thermostat, there is a spring inside the device which displaces everything. In any case, at room temperature, there is a connection from L1 to the bake and broil terminals so I know it's sending power through to those elements.
Not trusting anything about these electrical readings, I first plugged the oven into my Sencore PR57 isolation transformer. The transformer can only supply about 300 watts but I was more interested in measuring leakage current. No surprise when the low side leakage to the metal frame measured full deflection even with the power off to the oven. Not exactly the best situation. The high side leakage was zero. I turned up the voltage slowly and the current seemed to rise proportionately to the 17 ohm load until I stopped at about 300 watts. I should mention that the heating element did not seem to get warm. Also, the heating element impedance matched the load across the power plug so that seemed like a good sign.
Then I plugged it directly into the wall outlet via the Kill-A-Watt meter. I turned on the oven switch and an instant trip of the circuit breaker at the sub panel occurred. So where is all this extra current coming from to cook the ground plug on my Kill-A-Watt and trip the breaker? I must be missing something very obvious.
Thanks for your reply.
-- David Farber Los Osos, CA