Anybody know this is, it’s function, and necessity. It is between motor starte and motor.
Without getting down and dirty with the connections, and assuming the transformer is indeed
electrically between the starter and motor, my first guess would be a "poly phase buck-boost" transformer. The label on the incoming line indicates a 208 volt supply. A retrofit motor would likely be rated 240 volts. (or 240/480 nine wire, wired for low voltage)
A 240 motor will run on 208, but. . . It runs warm and does not produce full shaft HP. Older motors are often rated 208/220. Newer motors are rated 220/240, having less "iron", hence a weaker magnetic signature. From the looks of the installation, the machine came out of an industrial application. This would imply the necessity for full power at times. There are several other reasons for adding a buck-boost setup for the motor, I am just speculating the more likely.
The size of the wires versus the size of the transformer points to a low voltage (and high current) throughput. Buck-boost transformers are very common, and
relatively low cost. They are designed to add (or subtract) a given voltage to the line. 12/24 and 16/32 are the most common I have ever worked with. They are wired as an "auto-transformer" to, in common use, bring 208 volts up to 220 volts. (12 volts) They are also used to provide low voltage for controls and other uses. But in this install, most likely as a
buck-
boost. Simply put, if there are 3 wires in and three wires out, they may well be traced to the starter on one end and the motor on the other. And, unless burnt, safely ignored.
The purpose can often be tested easily enough.
Keep in mind, I am not going to try to troubleshoot your control system. One the control system is up to snuff, or at least functional, check the voltage at the motor (running) and at the starter. If they differ by some nominal amount, 12/24 or 16/32 volts, the transformer is indeed set up as a boost. If you have a 220/240 volt supply, the voltage at the motor may be too high, At 240, the voltage supplied to the motor may be as high as 264 volts. It would be fine at 208 volts, but for a 240 supply, run a little hot. In most cases, especially for "casual" use, high voltage won't have any immediate effect. But for running all day, it will "cook out" the motor.
At the bottom line, without a visual inspection,
this is pure speculation. It is not intended as any more than guidance for following up the circuit.
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