Interference of frequency converters on shielded pump shaft monitors
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Hello everyone, after installing a frequency converter on a shielded pump, the pointer on the shaft monitoring device shows a red value. I would like to ask how the frequency converter causes interference with the shaft monitoring device. Thank you!
It is estimated that when the speed drops too much, the oil film thins out and the rotor descends significantly; as a result, the shaft monitor detects that the downward movement deviates from the set values, causing the indicator to shift into the red zone. In the red zone, according to the factory requirements, it means the bearing is worn out.
There are some reasons for this, but it’s still in the red zone when operating at the rated speed
So, is the pump actually already in a worn condition? What happens after the variable frequency drive is turned off?
The reduced induced current resulting from bearing wear and misalignment causes the pointer of the bearing detector to stay in the red zone.
Which factory is it from? Axis monitors produced by different manufacturers vary, and even those from the same manufacturer come in several types (mechanical, electronic, etc.)
Bearings monitors from the Empire series, such as Dalian Empire and Dalian Huanyou, display the voltage output via modules on the monitor (TRG gauge) ； If a module is designed to be used at line frequency, it will definitely give incorrect readings under variable-frequency operating conditions; therefore, there are two ways to correct this: 1. Remove the power supply, or 2. Replace it with a module that can be used under variable-frequency conditions
Are there any abnormalities in pump operation during the red zone, such as vibration? Unusual noise? Fever?
There are no abnormalities; it’s just that the gauge pointer is in the red zone. The problem is that the red zone in the manufacturing plant constitutes a hazardous area, and its use is not permitted. It represents a potential hazard that must be eliminated during inspections – under normal operating conditions, when the bearing wears down to its limit, it shows up as a red zone; therefore, this issue must be resolved as soon as possible
There are no abnormalities; the manufacturer stated that it is necessary to replace the shaft monitor module compatible with the inverter