In some conditions of the power supply chain, electrical resonance phenomena may occur in motor windings.
These phenomena can multiply several times the instantaneous voltage of winding versus ground, leading to excessive stress of the motor insulation system resulting in quick degeneration and total insulation failure after a short time of operation.
Picture below shows the star point voltage versus ground waveform acquired in a system with significant resonance. The DC-Bus setting of the power amplifier is only 600 Vdc but the instantaneous voltage can reach a value as high as 1600 V. The insulation system cannot withstand this high voltage in long term operation.
To limit such voltage transients, Phase supplies with each motor with such characteristics a tuned anti resonance filter (snubber) which must be assembled within 5 m of the motors, star terminal (white wire) and machine ground. Failure to connect the snubber may result in motor failure by insulator puncturing. Phase can supply different type of snubber depending on motor size.
NOTE: larger snubbers in normal opera 200W) and need to be mounted on a cooling surface. Check this requirement on the snubber drawing.
Also PMC suggest , in the first installation, to check the temperature of the snubber that do not exceed 90°C.
On request Phase can supply special snubbers with a channel for liquid cooling.