Hi, this is Archer72, for another episode of Hacker Public Radio.

In this episode, I try to head down memory lane in my experience or lack of it.

This need to recall my memories was in part from a comment by Whiskeyjack on Robots and Industrial drives.

While I don’t have direct experience with robotics, this was an interesting enough field to explore based on my limited knowledge. I won’t mention robotics, with the exception of a one year stint at a workplace called Fanuc. This location in Illinois dealt with the drives that may have powered the robots that the company featured, but I have no direct interfacing with these machines.

The area of work that I seem to have been drawn to several times is the one repairing industrial spindles, servos and power supplies. Also there is a phantom memory of a company that used VFD’s or Variable Frequency Drives to power some fountains in Las Vegas. I did a little digging into my history of social security payments to try and recall this area of work, as I am in the United States, and the government keeps records back to my first job 35 years ago.

United States Social Security History

Sign in with ID.me > Go to Home > Review your full earnings record now > Click to close Privacy Act Statement > Not sure if you need to request a correction? > View Details on Every Single Entry , no nicely compiled list.

Explanation

I should back up and explain a few things. Some types of industrial equipment that I have some experience in can be related to something more familiar.

1. VFD’s, otherwise known as variable frequency drives

• A variable frequency drive (VFD) is an essential motor controller used in various applications to manage the speed and torque of AC motors
• A practical computer example is to vary the speed of desktop fans to correspond with the temperature of the CPU and inside the case

2. Stepper motors
   • Stepper motors in an industrial setting are a type that I do not have experience, but would welcome input about possible applications in this field
   • Practical application
     • Stepper motors have a familiar application
       • 3d printing application of the filament to the print bed

3. Servo Drives
   • Servos in an industrial setting are a type of control amplifier, using precise control for up to 6 motor axis
   • Practical application
     • Servos have two familiar applications
       • Reading and writing data to a floppy disk. Initially, servos were used for the ‘standard’ floppies until the higher density format was introduced.
         After that, stepper motors were used for increased accuracy of the read/write head.
       • 3d printing application of the filament to the print bed in higher end (read, more expensive) 3d printers
       • Mechanical hard drives
         • Mechanical hard drives (HDDs) utilize a servo system to manage the positioning of the read/write head over the disk platters. This system is crucial for accurate data retrieval and storage.

4. Power supply modules in an industrial setting
   • Two types that I have encountered
     • 480 VAC
     • 240 VAC
   • Theory of operation

     • In a 480 VAC industrial power supply, the incoming three-phase 480 VAC is first rectified to a nominal DC bus voltage of about 650–680 VDC. The electrical conversion from AC to DC is performed by feeding the AC through a set of three I.G.B.T modules, one for each phase of AC. DC-link capacitors then smooth the rectified voltage with and electrolytic capacitor, usually ranging from 2000 µF to 4000 µF depending on the specific requirements of the system

       I.G.B.T is short for Insulated gate bipolar transistor , and is the building block of industrial drives.
       This applies not only to PSM (Power Supply Modules), but are part of Spindle and Servo amplifiers.

Real world experience

The first time I repaired spindles in the workforce was a year long job in 2010. The spindle drives that we repaired did not have great quality parts, that were sourced as used parts on Ebay. The drives that we repaired were for the Yaskawa company headquartered in Japan.

The only repair that is memorable there was when I traced the drive not powering up to a burnt signal trace leading to the microprocessor.

The second time doing this type of job was in 2022 with Fanuc , this time for another year with spindle drives, servo amplifier and related power supplies.
Most of the units were supplied with 480 volts, while on the low voltage benches they were 240 volts.

There were a couple of times that the 3 phase power leads, labeled as R, S and T were reversed leading to the power supply. This caused the inrush resistor to do it’s designated job and blow out in a similar way to a fuse. This part is made of a ceramic outer layer and a sandy type inner layer, which is a mess with overcurrent.

The other type of catastrophic failure that I would see frequently before powering up the on the bench was that the I.G.B.T. modules were blown out due to the excess regenerative braking voltage feeding back in these type of power transistors.

Overvoltage conditions can arise from:

Regeneration:

When a motor decelerates rapidly, it can send energy back into the drive, increasing the DC bus voltage.

Transient Events:

Lightning strikes, utility switching, or large motor starts can cause instantaneous voltage spikes.

There were a few times that the IGBT’s were blown out with enough force to expose the gel that was insulating the part.

Robotic demonstration:

During the time at this company, there was a trade show demostrating the Robotics side of the business. The Fanuc M-2000iA robot was shown lifting and maneuvering a Corvette.

CNC Control panel example

CC Attribution to : CNC Control panel : 3d model

Unsure of CC license so will link the photo of a Fanuc drive here

Drive : Fanuc A06B-6110-H026

Additional resources:

Manuals

Fanuc AC Servo & Spindle Motor, and Servo Amplifier Manuals by Fanuc LTD

Fanuc Series 30i (and others) CNC Controller Manual Collection by Fanuc LTD

Other pages

I couldn’t find a photo of catastrophic failure for this module, but you can see how this could make quite a mess!!

Iwaki 0381/A Resistor module 10 ohms

Reverse engineering: Failed IGBT

EngineeringDevotion : Topic 3: Braking Techniques : Free & Open Access

Electrical Flux lab : Phase Symbol and Color code reference

Wikipedia : G Commands (Croatian)