electricthermostat
I came across this rather strange looking thermometer. It seems to have two scales and some kind of wires inside it.
There are two terminals at the top. Is it a thermostat? But it seems to be too long for one. Should be at least an arm length.
It seems to be very old to as I was unable to find anything on google about it with its name or data on it.
Update:
The fan doesn't produce heat, but if the fan never blows, the heating element might overheat and start a fire.
Thermostats fail. Safety regulations generally work on a "single fault" principle. Meaning no single fault in a product should lead to a safety hazard. In this case, the thermal fuse provides a backup to prevent a fire in case the thermostat fails (or, as @winny points out, in case the fan is mechanically blocked).
Each of the three power lines for a delta connection must be connected to one end of two of three phase coils. That is what is shown.
For a wye connection, each of the three power lines must be connected to one end of one of the three phase coil. The other end of each phase coil must be connected together to form a neutral. There is no external connection to the neutral. That connection would be made if the three jumper links were to be removed and replaced to connect together either the red, orange and yellow leads or the blue green and black leads. The three leads without jumper links would be the power connections. Only two links would be required, but the third would be stored on top of one of the other two.
The wye connection would look something like this:
Best Answer
Yes, it is a thermometer that is used in water-based thermostats. There is a tiny wire attached to a magnet inside on a threaded rod, and the top knob has a magnet, so when rotating the top you can move the wire position relative to mercury level. This makes an on-off switch that is used by electronics to control bathtub heater.
ADDITION: This device is called "mercury contact thermometer", or "glass contact thermometer", and they are still in use, example here. From the link, contact rating is 20 mA 36 V. Here is another one,