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- Jan 6, 2017
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- 1,214
I got a Seimens 1.5kw 3 phase motor on ebay for a good price. I've got the bracketing adapted, it's all mounted up and the belt adjusted. Now I'm in the process of wiring it up.
Even though my lathe is significantly different than the PM1440, I'm still staying fairly close to the methods and diagrams @mksj was kind enough to make available in the Precision Mathews forum.
So, my control panel has a 4 way jog joystick, a dual no/nc led equipped power switch, a dual no/nc E-stop switch, a 5k potentiometer and a hall effect tachometer.
Since I'm still waiting for several of the switches in the mail, i've been testing and setting up the parameters using some toggle switches temporarily wired to the external command terminals.
The 4 way jog joystick is set up with the up/down directions set to run the motor forward/reverse @ the frequency setting of the potentiometer, with the normal run braking rate. The joysticks left/right directions are currently set to run the motor forward/reverse @ a preset 30hz, and braking set to 1 second. I've tested these settings in each gear, and they work perfectly.
I'm routing the 24v com for all external commands directly from the vfd to the main contactor first, which drops-out when the e-stop is triggered. So, E-stop opens that contactor, which kills both the 24v circuit to the vfd external commands, and also opens both the forward and reverse contactors. The contactors are still wired using the stock coil connections, just with the high voltage motor wiring removed
After the main contactor, the 24v vfd com is tapped for/to the common terminal of the joystick, then goes in parallel, into the forward and reverse contactors. Each of the forward reverse contactors then have output wires to the s1(forward) and s2(reverse) inputs on the vfd.
So, the apron lever still controls the interlocked contactors in stock form. Down closes the fw contactor, connecting 24v com to the vfd s1. Up, closes the rev contactor, connecting the 24v com to the vfd s2. If e-stop is triggered while the apron lever is engaged, all contactors drop-out, and cannot be re-engaged unless both the apron lever and estop is reset.
The 24v com for the jog joystick is tapped after the main contactor, but before the fw / rev contactors. So, the jog functions bypass the fw/rev contactors, but are still killed when the e-stop opens the main contactor. The 2nd no/nc pole on the e-stop is wired n/o, and sends the 24v com to the vfd s5 (brake to stop and reset).
So, my question is:
Should I be using the Estop as I currently am, to open the contactors that control the 24v signal to the fw/rev (s1 and s2) and jog (s1, s2, s3 and s4). Kinda the stock configuration already, just with low voltage signals now instead of high voltage motor power wires?
Or should I have the Estop killing power the the VFD itself?
The reason I hesitate to wire the Estop to kill vfd power, is because I would lose motor braking after hitting the Estop. Without power, the motor would coast down.
As I have it now, hitting e-stop opens all contactors, cutting the 24v signal to the vfd inputs, and closes the 24v signal to the s5 (reset/stop) terminal. The Estop and apron lever must both be reset before the contactors will work again.
But, in this configuration the vfd still has power. I'm trusting the vfd software to actually turn-off the motor when the contactors open and cut the signal source.
Which is better/safer? Kill the vfd input signals and trust the vfd to stop the motor, but still have motor braking?
Or kill power to the vfd. Don't have to trust the vfd software, as no power will definitely turn the motor off, but lose motor braking?
I could wire the Estop to open the contactors AND kill power to the vfd. But, I'd still lose motor braking?
Thoughts?
Even though my lathe is significantly different than the PM1440, I'm still staying fairly close to the methods and diagrams @mksj was kind enough to make available in the Precision Mathews forum.
So, my control panel has a 4 way jog joystick, a dual no/nc led equipped power switch, a dual no/nc E-stop switch, a 5k potentiometer and a hall effect tachometer.
Since I'm still waiting for several of the switches in the mail, i've been testing and setting up the parameters using some toggle switches temporarily wired to the external command terminals.
The 4 way jog joystick is set up with the up/down directions set to run the motor forward/reverse @ the frequency setting of the potentiometer, with the normal run braking rate. The joysticks left/right directions are currently set to run the motor forward/reverse @ a preset 30hz, and braking set to 1 second. I've tested these settings in each gear, and they work perfectly.
I'm routing the 24v com for all external commands directly from the vfd to the main contactor first, which drops-out when the e-stop is triggered. So, E-stop opens that contactor, which kills both the 24v circuit to the vfd external commands, and also opens both the forward and reverse contactors. The contactors are still wired using the stock coil connections, just with the high voltage motor wiring removed
After the main contactor, the 24v vfd com is tapped for/to the common terminal of the joystick, then goes in parallel, into the forward and reverse contactors. Each of the forward reverse contactors then have output wires to the s1(forward) and s2(reverse) inputs on the vfd.
So, the apron lever still controls the interlocked contactors in stock form. Down closes the fw contactor, connecting 24v com to the vfd s1. Up, closes the rev contactor, connecting the 24v com to the vfd s2. If e-stop is triggered while the apron lever is engaged, all contactors drop-out, and cannot be re-engaged unless both the apron lever and estop is reset.
The 24v com for the jog joystick is tapped after the main contactor, but before the fw / rev contactors. So, the jog functions bypass the fw/rev contactors, but are still killed when the e-stop opens the main contactor. The 2nd no/nc pole on the e-stop is wired n/o, and sends the 24v com to the vfd s5 (brake to stop and reset).
So, my question is:
Should I be using the Estop as I currently am, to open the contactors that control the 24v signal to the fw/rev (s1 and s2) and jog (s1, s2, s3 and s4). Kinda the stock configuration already, just with low voltage signals now instead of high voltage motor power wires?
Or should I have the Estop killing power the the VFD itself?
The reason I hesitate to wire the Estop to kill vfd power, is because I would lose motor braking after hitting the Estop. Without power, the motor would coast down.
As I have it now, hitting e-stop opens all contactors, cutting the 24v signal to the vfd inputs, and closes the 24v signal to the s5 (reset/stop) terminal. The Estop and apron lever must both be reset before the contactors will work again.
But, in this configuration the vfd still has power. I'm trusting the vfd software to actually turn-off the motor when the contactors open and cut the signal source.
Which is better/safer? Kill the vfd input signals and trust the vfd to stop the motor, but still have motor braking?
Or kill power to the vfd. Don't have to trust the vfd software, as no power will definitely turn the motor off, but lose motor braking?
I could wire the Estop to open the contactors AND kill power to the vfd. But, I'd still lose motor braking?
Thoughts?
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