Hi guys,
I have a lathe with a 15kw / 18.5 kw Fanuc AC spindle motor without nameplate from -85.
The AC spindle drive is Fanuc A06B-6044-H742. This drive also powers a Fanuc Spindle motor with 2.2 kw / 3.7 kw power which drives the live tool spindle.
There are a few different problems which may be related as they were discovered in the same week.
1. With main spindle engaged in high gear and 30 rpm the spindle motor gives one high pitched noise per revolution. Torque should not be fantastic at 30 rpm on high gear but I can stop the spindle with my hand. At higher rpm the program stops with ALARM 2 on spindle drive after 1-3 minutes.
There is no noise turning the spindle by hand. If belts are disconnected the motor shaft spins smooth by hand with no noise.
With spindle disconnected I figured out that 1170 rpm in high gear from MDI gives 1508 rpm on the motor shaft. The motor have the same little high pitched noise for every revolution but it is or course hard to hear at this rpm. Other than that the motor is running smooth without alarms. During this test I noted the following:
Frequency is 1400- 1600 hz (fluctuating on cheap DMM)
Voltage is about 125 between all legs but current is not even: U=17 amp, V=6 amp and W=21 amp. Is this normal or should current be the same for all legs?
Motor resistance between windings is 0.1 ohm including motor wires between all legs. Megger tests are very strange. Only motor is U - G = 300 meg, V - G 276 meg and W-G 388 meg ohm. Motor wires disconnected from everything is 700 - 1000 meg ohm. When testing wire and motor but disconnected from drive I get around 120 megohm on all legs. I should ad that we have 32 degree C and 85 - 90 RH here and we are half a click from the ocean so the air is damp and salty. With megger ground clip on frame and the positive test lead in the air 1/2" from the frame I get 400 - 500 megohm. Anyway the meg readings are about the same as they were a year ago.
I don't have a nameplate on the motor, but found a picture of one on the net for a Model 15 motor which has the same power rating.
Volt 200 3 ph, 4 pole induction. RPM 1500 / 4500, amp min. 60/70, 15 kw /18.5 kw. As I need to figure out if I have a motor or drive problem (or both) I hooked the motor to the incoming 220 VAC 3 phase at 50 hz for 1 minutes and got about 1570 rpm and a steady U - 103, V - 105 and W - 106 amps.
I dont know how to interpret the Fanuc nameplate though. Some say amps are during no load, others say full load. I tried to find out if JEC 37 differs from NEMA but got nowhere. Does anyone know if the current draw is abnormally high or if it is ok?
Maybe the nameplate amps are not applicable for running at 50 hz from wall power?
2. When the spindle drive is running the smaller live tool motor everything is ok up to 1400 rpm. Over this an oscillation kicks in which pulls down the rpm slightly in a pulse of one per every 6 revolution of the spindle. There is no high / low gear on this spindle. The oscillation is pushing the Fanuc 10T load meter to 180% and after 1 minute I get the Alarm 2 on the spindle drive.
I get 60 meg ohm on all legs including wires to the live tool spindle motor. I have not checked this before so don't know if it is lower than before.
The winding to winding resistance is 1.4 ohm between all windings.
Again I just want to know which parts to focus on or send away for repair.
Since Alarm 2 is speed deviation and I get the same alarm for main and live tool spindle does anyone know if there is one common feed back circuit on the drive which handles both? If so I wonder if the feed back and speed deviation threshold can be adjusted individually for each encoder?
I should ad that each spindles have position coders hooked to the spindle drive.
3. Lastly the spindle orientation before engaging the C-axis rack is sometimes not working. It is much slower and the spindle hunts around before deciding where to stop. This never happened before.
Any help is greatly appreciated!
Andy
I have a lathe with a 15kw / 18.5 kw Fanuc AC spindle motor without nameplate from -85.
The AC spindle drive is Fanuc A06B-6044-H742. This drive also powers a Fanuc Spindle motor with 2.2 kw / 3.7 kw power which drives the live tool spindle.
There are a few different problems which may be related as they were discovered in the same week.
1. With main spindle engaged in high gear and 30 rpm the spindle motor gives one high pitched noise per revolution. Torque should not be fantastic at 30 rpm on high gear but I can stop the spindle with my hand. At higher rpm the program stops with ALARM 2 on spindle drive after 1-3 minutes.
There is no noise turning the spindle by hand. If belts are disconnected the motor shaft spins smooth by hand with no noise.
With spindle disconnected I figured out that 1170 rpm in high gear from MDI gives 1508 rpm on the motor shaft. The motor have the same little high pitched noise for every revolution but it is or course hard to hear at this rpm. Other than that the motor is running smooth without alarms. During this test I noted the following:
Frequency is 1400- 1600 hz (fluctuating on cheap DMM)
Voltage is about 125 between all legs but current is not even: U=17 amp, V=6 amp and W=21 amp. Is this normal or should current be the same for all legs?
Motor resistance between windings is 0.1 ohm including motor wires between all legs. Megger tests are very strange. Only motor is U - G = 300 meg, V - G 276 meg and W-G 388 meg ohm. Motor wires disconnected from everything is 700 - 1000 meg ohm. When testing wire and motor but disconnected from drive I get around 120 megohm on all legs. I should ad that we have 32 degree C and 85 - 90 RH here and we are half a click from the ocean so the air is damp and salty. With megger ground clip on frame and the positive test lead in the air 1/2" from the frame I get 400 - 500 megohm. Anyway the meg readings are about the same as they were a year ago.
I don't have a nameplate on the motor, but found a picture of one on the net for a Model 15 motor which has the same power rating.
Volt 200 3 ph, 4 pole induction. RPM 1500 / 4500, amp min. 60/70, 15 kw /18.5 kw. As I need to figure out if I have a motor or drive problem (or both) I hooked the motor to the incoming 220 VAC 3 phase at 50 hz for 1 minutes and got about 1570 rpm and a steady U - 103, V - 105 and W - 106 amps.
I dont know how to interpret the Fanuc nameplate though. Some say amps are during no load, others say full load. I tried to find out if JEC 37 differs from NEMA but got nowhere. Does anyone know if the current draw is abnormally high or if it is ok?
Maybe the nameplate amps are not applicable for running at 50 hz from wall power?
2. When the spindle drive is running the smaller live tool motor everything is ok up to 1400 rpm. Over this an oscillation kicks in which pulls down the rpm slightly in a pulse of one per every 6 revolution of the spindle. There is no high / low gear on this spindle. The oscillation is pushing the Fanuc 10T load meter to 180% and after 1 minute I get the Alarm 2 on the spindle drive.
I get 60 meg ohm on all legs including wires to the live tool spindle motor. I have not checked this before so don't know if it is lower than before.
The winding to winding resistance is 1.4 ohm between all windings.
Again I just want to know which parts to focus on or send away for repair.
Since Alarm 2 is speed deviation and I get the same alarm for main and live tool spindle does anyone know if there is one common feed back circuit on the drive which handles both? If so I wonder if the feed back and speed deviation threshold can be adjusted individually for each encoder?
I should ad that each spindles have position coders hooked to the spindle drive.
3. Lastly the spindle orientation before engaging the C-axis rack is sometimes not working. It is much slower and the spindle hunts around before deciding where to stop. This never happened before.
Any help is greatly appreciated!
Andy