Yaskawa VS-626M5 machine tool spindle is the most innovative  spindle drive available from Yaskawa. The spindle drive consists of two components, the VS-626M5 inverter (M5) and the VS-626MR5 converter (MR5). The MR5 rectifies incoming AC voltage into DC voltage, while the M5 inverter outputs the simulated AC signal sent to the motor by means of pulse width modulation (PWM).

The DC bus bars connect the inverter and converter units that supply DC voltage to the inverter. 
 
Advantages of the M5 spindle are that they are high reliable, have high speed capabilities, and provide precise speed, torque, and current control; this enables the spindle to hold tight speed and torque tolerances. The converter regenerates all excess power directly to the incoming line, allowing for superior deceleration times as compared to regeneration via resistors. Quicker spindle deceleration yields faster tool changes, which results in increased machine productivity. All of these advanced features lead to a great product and design.
 
Common Failures - Causes and Troubleshooting Steps:
 
Most common causes of AL-01 overcurrents are:
 
1) Weak insulation on spindle motor/cables.
 
A megger is required to properly test insulation resistance. See our video here for additional help and tips related to megging a motor. Keep in mind that motor insulation usually decreases as it warms up. Ideally, the motor/cable is megged as soon as possible after the failure in order to get the most accurate megger readings possible
 
2) The M5 inverter has an issue with the outputs inside the drive. 
 
 This is another common failure that can be caused by weak insulation of the motor/cables, or can occur due to a parts failure within the drive.The best way to determine if your inverter has suffered a parts failure is to:
a) Disconnect motor leads U, V, and W, and then power on the machine. If the inverter still has AL-01, the outputs have been damaged. It is recommended to send your inverter and converter in for repair and get the motor inspected.
b) Using a multimeter, perform a static check similar to the procedure shown in our video here

When machines go down, it is important to be able to perform some basic troubleshooting. Finding exactly where the issues are can significantly reduce the time a machine is down. Getting a better idea of what went wrong can also help repair shops when diagnosing and repairing issues on drives, motors, power supplies, and other machine parts.

Below are a few of the most important items to have on hand for diagnosing issues and performing preventative maintenance checks.

Essentials:

  • A multimeter is useful for checking voltages, both AC and DC. This is important when checking input voltages to drives or the voltages output from a power supply.  A multimeter can also be used to find short circuits using the meter’s continuity function or to measure small resistances (up to a few tens of M).  Fluke and Hioki make reliable and highly recommended multimeters.
  • A megohm meter, also known commonly as a megger, is a device for testing the resistance to ground. This is for determining if a motor, plug or cable is bad or beginning to fail. This device measures resistance above 1,000 M and can show any failures or degradation in motor winding insulation. We recommend motors have at least 200 M between each phase (U, V, W) and ground.
  • A current clamp has a set of “jaws” which open to clamp around a conductor. A current clamp is great for checking to see if current in 3 phase devices is balanced. Many current clamps can also be set to capture maximums in current spikes to catch irregularities when starting or stopping a device.

Additional:

  • Thermal imaging/infrared cameras are widely used for diagnostics and troubleshooting. A thermal camera can show areas that are becoming excessively hot or burned which can be the underlying cause for component failure. It can used to check contactors or motors to find hot spots that may be of concern.
  • A vibration analyzer can be used to check if your motor bearings have gone bad. This device can identify vibration peaks on a motor and the will look for patterns in the vibration. A vibration analyzer can determine the condition of the bearings which will allow the user to schedule preventative maintenance or plan for repair.

Make sure to follow all proper safety guidelines when taking any measurements on machine parts, both with power and without power. Voltages used in these devices can be lethal. If you are unfamiliar with using these measurement devices or uncomfortable with taking these measurements yourself, seek training or consider hiring a certified technician who can assist with on-site measurements and troubleshooting.

At Precision Zone, we guide our clients towards to best decision that serves their business. If you have specific repair or replacement questions, get in touch with our expert customer support team at 800-551-4420 or repair@precisionzone.com

 

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