I have a Okuma LB 15 lathe with OSP5000L-G control and Fanuc AC spindle drive type A06B-6055-H208 with top pcb type A20B-1001-0120. In this machine, spindle do not have power at low rpm (600) in high gear. When I checked the motor current, it has already reached its maximum current of 40 Amps and because of that, the spindle speed drops and finally stops. It is working normal at higher speeds in high gear. Also, at low gear, it works ok. I have seen the rpm shown on the monitor and spindle drive different. Spindle drive shows 50 % more speed than the rpm shown in monitor both in low and high gear. The spindle drive works ok until its rated motor current of 40 amps. At that time, I see the input current to drive is about 13 Amps. Can anybody suggest any solution for this problem ?
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