Hydrogen pump trip

1. First, how do you determine that the actual temperature has not risen? 2. Check the grounding shield ； 3. Check the cable ； 4. To address such fluctuations, adding a transmitter at the sensor end improves interference resistance

If the value rises within 5 seconds, check the records to see the interval between samples taken. DCS systems usually take samples every few seconds before sending data; observe the rate of increase. If the value rises within one or two sampling periods, possible causes include poor contact or the sensor touching the ground. If it indeed rises within about 5 seconds, consider whether there are high-power motors in the cable tray, especially those equipped with frequency converters. In such cases, it might be necessary to replace the transmitter with one from a reputable manufacturer like Siemens or E+H, as these models have excellent interference resistance

　　∵The temperatures of the front and rear bearings of both pumps increased simultaneously, and those of the other pump also rose. 　　∴It is highly suspected that abnormal process operation caused an increase in pump load. 　　The claim that the temperature at the site did not actually rise is untrustworthy; the sensors used to measure shaft temperature are inserted into the shaft bearings, so a short-term increase in temperature cannot be detected from the outside. 　

For these few temperature points, we are looking at the trend over one minute; it’s not visible on the chart, but it’s listed in the alarm messages as if it were an instantaneous value. There are many temperature sensors connected to this temperature card board, and the temperatures of all the others haven’t increased at all – it’s really strange

The rise and fall of temperature is a slow process, but here it goes up and down in just a few seconds.

After the trip, process technicians conducted on-site measurements and said the temperature was not high. Later, we ran this pump alone for over half an hour, and the temperature changed very little

　　You can’t apply the concept of using a container for heating to bearing shells. It can take just a few hundredths of a second for large machinery to go from normal operation to sudden bearing burnout. 　　You can go to the rotating equipment section to inquire about the temperature rise that occurs in cases of bearing failure and abnormal bearing cooling. 　　I once encountered a situation where an alarm was triggered due to high shaft temperature in a hydrogen compressor, but the cause could not be identified; after installing a flow switch at the pump outlet, the initial alarm that triggered in such cases changed from one related to shaft temperature to one related to flow rate. 　　 　　The possible causes may vary depending on the situation; I’m just reminding you to pay attention to this aspect, as the actual identification of the cause will require on-site analysis.