Bridgeport milling machine 3 phase motor protection

I am getting ready to upgrade the wiring on my new to me Bridgeport mill. I am powering the mill with my rotary phase converter. The way the mill is currently wired power goes to a main disconnect(no fuses or overloads) and then branches off to separate switches on the back of the column that have overload protection built into them for the head, coolant pump, and the power feed for the table. Power goes from those switches to each respective motor on the machine. The head and power feed each have an additional switch for off, forward, reverse.
The overload protection in the switches only monitors and switches two of the three phases. The third leg is not switched or monitored for load which leads me to belive that this mill was probably originally fed from a corner grounded delta supply which I don't have. Because the head and the power feed for the table have separate switches on them I would like to eliminate the switches that have the overload since they are redundant from a switching standpoint and old and replace them with just some form of overload protection. The head is 1 hp, the coolant pump is 1/4 hp, and the power feed is 1/8 hp. The loads from these motors are so small that my search for overload relays that do not have contactors has given few results. I am tempted to use three pole fuse blocks with time delay fuses for each of the motors in a cabinet on the mill. Is there a different option that I am missing? I don't like not having the third phase monitored for overload. Am I over thinking this?

Thanks!

Ebay has a number of overload relays, some are free standing, some have stubs to connect to a contactor. These for the most part are adjustable thermal relays of the IEC style (no replaceable heaters). The stubbed style could be used by either interfacing the the machine wiring and ol with a terminal board or pigtailing a wire soldered to the stub covered with heat shrink tubing.

Sample page, sorting by the cheapest first.

eBay - Page Not Found

Tom

Yes you are over thinking it but not by much. Props to YOU for even thinking. However, it is really hard to get wound about that 3rd legger when you gotta have one of the other two to dance. Really, unless you have a neutral in that dance, those are ALL phase to phase loads so either sees the same load. However, the dance ends when you need to kill the music and realize there is still a drink bitch still dancing. You have to make sure if things stop (for a reason), that the wild one stops too.

It it VERY not uncommon to monitor 2/3 phases. Just make sure they all kick out together though. Sounds like you can figure that out.

The 2 OL heaters instead of 3 was the norm up until about 1978, which is when the NEC changed to require OL protection on all 3 legs (regardless of the 3 phase source) in article 430.37. So all it really means is that your controls are older than that.

The issue of not having to provide something in a grounded leg is about Over CURRENT protection, i.e. fuses, not Over LOAD protection for motors. Now you must have OL protection in all three phases of a 3 phase starter.

Jraef said:

The 2 OL heaters instead of 3 was the norm up until about 1978, which is when the NEC changed to require OL protection on all 3 legs (regardless of the 3 phase source) in article 430.37. So all it really means is that your controls are older than that.

The issue of not having to provide something in a grounded leg is about Over CURRENT protection, i.e. fuses, not Over LOAD protection for motors. Now you must have OL protection in all three phases of a 3 phase starter.

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I will take your word for the NEC change as late as 1978. NEMA changed from 2 to 3 ol's in the 60's, 1964 I think. In 1966 GE came out with the 200 line control which was the 100 line with a different OL relay. The other manufacturers did the same at about the same time.

Tom