Do you have any way to monitor the oil level in the sump where the submersible pump is located? It is possible that air is getting into the pump, and the time lag is caused by the pump momentarily "losing its prime" and/or introducing air into the lubrication lines.
I sincerely hope this helps.
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Daniel K Corman, CMRP
Houston, Texas, USA
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Original Message:
Sent: 06-24-2023 04:47 AM
From: Mohammad Shnyour
Subject: Turbine Lubrication Oil Pump
Hey All,
I just wanted to share with you an issue we are having in our facility to take advantage of your experience.
A DC Submersible pump is implemented in the steam turbine lubrication oil system to provide a flow with pressure 1.5 bar. Recently, the pressure switch activation signal of the discharge line is delayed to reach the setpoint (1.5 bar). but this does not happen every time, In some cases the pressure reaches the setpoint immediately and sometimes within 10 seconds.
As a first action, we installed a pressure gauge on the vent port of the pressure switch to ensure that the pressure switch is not defected and the same results repeated as follows:
# Sometimes the pressure was built up immediately from vacuum to 1.5 bar.
# On the other hand, sometimes it takes more than 30 seconds to reach the setpoint.
In all attempts, when the pressure gauge read the setpoint the pressure switch activated directly.
So, if anyone has experienced this type of problem or has any suggested solution or root cause. I would be grateful if you could share it with me.
Thank You