Harrison Alpha 550 - Servo alarm

[Marvv89]

We have problems with our Harrison Alpha 550 lathe, with GE Fanuc FS-16 and A16B amplifiers.

I contacted Harrison, we checked everything we can but they can't help us anymore. So I am calling the help of this forum in now.

The following alarms come up:

Messages:
401: VRDY OFF
414: AXIS DETECT ERR

For both Z and X.

The contactor K3 comes up, but when I want to move the silders to move the axis motors it falls off. And the LED HC @ the amplifier lights up. So that is a High current alarm.

What we tried to solve them:

- Swapped the amplifiers (A31, A32) with the ones out of our Harrison Alpha 460 -> OK
- Swapped the main controlling unit (A1) -> OK
- Swapped the contactor K3 -> OK
- Swapped the motors -> OK
- Swapped the encoder and encoder cable -> OK
- Swapped the PSU filters, makes no sense -> OK
- Checked all the fuses -> OK
- Reviewed all the digital servo parameters from the 550 with the 460
- Checked the axis/motors turning well and smooth by hand -> OK
- Measured the input voltages: 380V / 220V
- Measured voltages of A1 (24V) A31 (244V) and A32 (244V)
- Measured the current trough the motors, it's i about 400 mA/140V stationary, about 500/600 mA/140V when trying to move the slider. Measured it in de 460 and is was about the same, going up to 900 mA/140V.
- Measured input current to the amplifiers, max 0.16A
- No shortcuts between motor connections, to ground neither
- Front slider pot-meter swapped -> ok
- Measured resistance of the cable to the front pot-meter -> ok, only 1 to ground, no shortcuts

The values of the diagnostic registers 200, 201 etc are:

Bit 7 6 5 4 3 2 1 0
200 - X 0 0 0 0 0 0 0 0
200 - Z 0 0 0 1 0 0 0 0

201 - X 0 0 0 0 0 0 0 0
201 - Z 0 0 0 1 0 0 0 0

202 - X 0 0 0 0 0 0 0 0
202 - Z 0 0 0 0 0 0 0 0

203 - X 0 0 0 0 0 0 0 0
203 - Z 0 0 0 0 0 0 0 0

204 - X 0 0 0 0 0 0 0 0
204 - Z 0 0 0 0 0 0 0 0

So as the diagnostics say it must be a overcurrent alarm (PSM)?

When I check the servo tuning screen, I see the current (%) is dancing around from 1, 2% up to 60 to 80% while the machine is idle, while I am jumping to the parameters in the servo tuning screen. When I measure the current, it is stationairy about the above values while the percentages are dancing like above. So I don't know why this is. To me the current sensing seems to be broken. But I would say that can't be, because A1, A31 and A32 are OK.

Hope someone can help us.

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[underthetire]

Did you check the motor power cable with a mega ohmer? You say you switched encoder cables, but did you also switch power cables?

[Marvv89]

Underthetire,

I did, checked for connections between the phases and ground. No shortcuts for both axis.