Vernon Tuck
Stainless
- Joined
- Oct 26, 2008
- Location
- Brenham, Texas
Gentlemen,
A few years ago, I bought a mid 80s Bridgeport Series 1 2J manually operated mill. It did come with a DRO and power feeds on X and Y. It was a Pratt and Whitney surplus item.
I am laying plans to install electric power to the mill from a 200 amp 240V single phase service input to an SJ200 (3HP) inverter. I am well aware this topic has been discussed here and as far as I know I have carefully read all those discussions.
This post mostly contains some "loose end" questions that may have already been dealt with. I will be doing the installation myself. However, I hope y'all will help me understand so that I don't let any of the smoke leak out.
First, the power feeds: The table has a motor driven rapid traverse on X and outputs position data to a DRO. The body of the mill was heavily painted over and these data plates are hard to read. However, as best I can tell, both motor drives are designed to run at 90V DC. However, the cords running out of them appear to be standard 3 prong 120V AC plugs.
Question (group) number 1: Can that be right? Admittedly I have no experience with mills or DC powered equipment. But these plugs appear to be independent of the mill motor wiring itself. Is it likely that there is an AC to DC transformer within the motor drives themselves? Or are those cords to be plugged into some kind of DC power supply? Forgive my ignorance here.
Question (group) number 2: As to the mill itself it has the following electric components installed: A) a single phase 240V to 120V transformer mounted on the back of the base. This transformer is wired into
B) a magnetic switch box mounted on the lower left side of the pedestal (facing the machine). The switch box has a set of wires running through flexible non-metalic conduit that run up the left side. These terminate at
C) a 3 position (LOW) unmarked "middle" and HIGH range pointed rotary switch. Also coming out of B) ("switch box") is a
D) 3 button box. Two buttons are red and one is green. The lowest button (red) is labeled "EMERGENCY STOP - PULL TO RESET"). The second button (red) is labeled "STOP" and the green button "GO". No explanation needed there.
Otherwise, I can see no other electric controls on the mill. I have not yet clambered up to the motor head for a look so I don't know if the machine is now wired for 230V, 460V or something else.
Now it is my understanding that most or all of those components will have nothing to do with the VFD conversion and that they might as well be removed. However, I seem to have seen discussions of people using the button box and wiring the STOP (or is it the EMERGENCY STOP?) button into the VFD input circuit so as to be able to quickly kill power to the mill in event of a mishap. Is this right?
Also, I have a set of questions that have to do with "conditioning" the power that flows through the VFD to the mill, whose motor is not "VFD rated".
I have read in a couple of places that the best wiring to use for the motor feeds is called "cross linked polyethylene" or "XLPE" or "PEX" cable or wire. The explanations were all over my head but I was given to understand that this wire, run in shielded, non-metallic trays, is to be much preferred.
Finally, "AC input and output "reactors" also known as "chokes". My understanding is that these are worth using for this kind of installation. In my case we are in a rural location and the power goes down or browns out with fair frequency. Apparently, the input choke serves to protect the VFD. The output choke, which is the same kind of device, except that it will take single or 3 phase inputs, serves a similar purpose on the load side of the VFD.
Anyway, I just ordered a couple. So please don't anybody tell me I don't need 'em ha ha!
So, in summary, does anything I set forth above make anybody scream NOOO!!!?
Otherwise, if nothing else, I will appreciate being set straight on how the motor drives on a Bridgeport are normally fed.
Thanks,
Vernon
A few years ago, I bought a mid 80s Bridgeport Series 1 2J manually operated mill. It did come with a DRO and power feeds on X and Y. It was a Pratt and Whitney surplus item.
I am laying plans to install electric power to the mill from a 200 amp 240V single phase service input to an SJ200 (3HP) inverter. I am well aware this topic has been discussed here and as far as I know I have carefully read all those discussions.
This post mostly contains some "loose end" questions that may have already been dealt with. I will be doing the installation myself. However, I hope y'all will help me understand so that I don't let any of the smoke leak out.
First, the power feeds: The table has a motor driven rapid traverse on X and outputs position data to a DRO. The body of the mill was heavily painted over and these data plates are hard to read. However, as best I can tell, both motor drives are designed to run at 90V DC. However, the cords running out of them appear to be standard 3 prong 120V AC plugs.
Question (group) number 1: Can that be right? Admittedly I have no experience with mills or DC powered equipment. But these plugs appear to be independent of the mill motor wiring itself. Is it likely that there is an AC to DC transformer within the motor drives themselves? Or are those cords to be plugged into some kind of DC power supply? Forgive my ignorance here.
Question (group) number 2: As to the mill itself it has the following electric components installed: A) a single phase 240V to 120V transformer mounted on the back of the base. This transformer is wired into
B) a magnetic switch box mounted on the lower left side of the pedestal (facing the machine). The switch box has a set of wires running through flexible non-metalic conduit that run up the left side. These terminate at
C) a 3 position (LOW) unmarked "middle" and HIGH range pointed rotary switch. Also coming out of B) ("switch box") is a
D) 3 button box. Two buttons are red and one is green. The lowest button (red) is labeled "EMERGENCY STOP - PULL TO RESET"). The second button (red) is labeled "STOP" and the green button "GO". No explanation needed there.
Otherwise, I can see no other electric controls on the mill. I have not yet clambered up to the motor head for a look so I don't know if the machine is now wired for 230V, 460V or something else.
Now it is my understanding that most or all of those components will have nothing to do with the VFD conversion and that they might as well be removed. However, I seem to have seen discussions of people using the button box and wiring the STOP (or is it the EMERGENCY STOP?) button into the VFD input circuit so as to be able to quickly kill power to the mill in event of a mishap. Is this right?
Also, I have a set of questions that have to do with "conditioning" the power that flows through the VFD to the mill, whose motor is not "VFD rated".
I have read in a couple of places that the best wiring to use for the motor feeds is called "cross linked polyethylene" or "XLPE" or "PEX" cable or wire. The explanations were all over my head but I was given to understand that this wire, run in shielded, non-metallic trays, is to be much preferred.
Finally, "AC input and output "reactors" also known as "chokes". My understanding is that these are worth using for this kind of installation. In my case we are in a rural location and the power goes down or browns out with fair frequency. Apparently, the input choke serves to protect the VFD. The output choke, which is the same kind of device, except that it will take single or 3 phase inputs, serves a similar purpose on the load side of the VFD.
Anyway, I just ordered a couple. So please don't anybody tell me I don't need 'em ha ha!
So, in summary, does anything I set forth above make anybody scream NOOO!!!?
Otherwise, if nothing else, I will appreciate being set straight on how the motor drives on a Bridgeport are normally fed.
Thanks,
Vernon
