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dear team ,we are facing a problem in our cpp,where our unit tripped on gen defferential rpm, can any one explain me what is the problem and fault,and how is working? when this is act relay 86 B operated.
WHAT IS GENERATOR DIFFERENTIAL RPM ?
- Thread starter rajendra kumar madhukar
- Start date
@rajendra kumar madhukar,
Hmmmmm.....
An 86 device is usually a device that prevents automatically re-starting or re-synchronizing a machine (turbine-generator). An 86 device can usually be actuated by one or more devices that have detected a problem with the process or the machine (turbine or generator). The designation of 'B' in the device number you cited typically means there is an 86A device also. Many times the devices that actuate an 86 lockout relay are "grouped" together to actuate the lockout relays--for example, turbine-related sensors might actuate an 86A lockout relay, while generator-related devices (such as generator protective relays) might drive an 86B relay. Just about EVERY machine (prime mover and generator) has a unique lockout relay scheme, with many using the device number 86 without or without a suffix, and many machines have more than one lockout relay (I recall encountering one machine that had 11 lockout relays, most driven by a single sensor or device).
Do you have a device number for the relay that actuated the 86B lockout relay?
In my experience I have never encountered a generator protective device or -relay that monitored generator speed differential. I checked some lists of general device numbers and found none with a device called a generator differential speed or -RPM description.
For machines that are directly connected to each other (the turbine and the generator, that is) either with a single coupling or through some kind of speed-changing gear box, turbine speed and generator speed and generator terminal frequency are ALL DIRECTLY related, and when a machine is synchronized with other prime movers and generators on a transmission and distribution system ALL machines operate at the SAME frequency. If the system is running stably and without frequency deviations then all the machines run at a stable speed and the generators all have the same output frequency. NO machine in such a system--large or small!--can run at a different frequency than the other machines (for any appreciable length of time). [There are some very unique sets of circumstances which can result in one machine running for a split second or so at a different frequency than another machine on the grid--but they involve a LOT of very specific situations (such as the distance from the nearest generator on the system AND system voltage issues AND ... AND ...). In other words, in most parts of the world today these circumstances rarely ever occur--not never, but rarely. And you didn't tell us about any other protective relays (such as distance relays or current- or voltage differential relays) operating before or at the time of the incident.]
We don't know enough about the machine and its circumstances to provide much more information. Is the machine operating independently of any other generator, supplying a load or loads that are isolated from a larger grid and other machines?
What was the frequency of the system the machine was supplying at the time of the incident? What was the generator frequency at the time of the incident?
What was the system voltage at the time of the incident?
This is a steam turbine, with a boiler probably burning some kind of coal or wood products; was there any other problems with the steam turbine or steam supply which occurred before this 86B lockout relay was actuated?
Based on the information provided, there's just not much we can say. Occasionally, there are a couple of people who respond to threads/questions on Control.com who have some very unique experience and might be able to offer some assistance.
Hmmmmm.....
An 86 device is usually a device that prevents automatically re-starting or re-synchronizing a machine (turbine-generator). An 86 device can usually be actuated by one or more devices that have detected a problem with the process or the machine (turbine or generator). The designation of 'B' in the device number you cited typically means there is an 86A device also. Many times the devices that actuate an 86 lockout relay are "grouped" together to actuate the lockout relays--for example, turbine-related sensors might actuate an 86A lockout relay, while generator-related devices (such as generator protective relays) might drive an 86B relay. Just about EVERY machine (prime mover and generator) has a unique lockout relay scheme, with many using the device number 86 without or without a suffix, and many machines have more than one lockout relay (I recall encountering one machine that had 11 lockout relays, most driven by a single sensor or device).
Do you have a device number for the relay that actuated the 86B lockout relay?
In my experience I have never encountered a generator protective device or -relay that monitored generator speed differential. I checked some lists of general device numbers and found none with a device called a generator differential speed or -RPM description.
For machines that are directly connected to each other (the turbine and the generator, that is) either with a single coupling or through some kind of speed-changing gear box, turbine speed and generator speed and generator terminal frequency are ALL DIRECTLY related, and when a machine is synchronized with other prime movers and generators on a transmission and distribution system ALL machines operate at the SAME frequency. If the system is running stably and without frequency deviations then all the machines run at a stable speed and the generators all have the same output frequency. NO machine in such a system--large or small!--can run at a different frequency than the other machines (for any appreciable length of time). [There are some very unique sets of circumstances which can result in one machine running for a split second or so at a different frequency than another machine on the grid--but they involve a LOT of very specific situations (such as the distance from the nearest generator on the system AND system voltage issues AND ... AND ...). In other words, in most parts of the world today these circumstances rarely ever occur--not never, but rarely. And you didn't tell us about any other protective relays (such as distance relays or current- or voltage differential relays) operating before or at the time of the incident.]
We don't know enough about the machine and its circumstances to provide much more information. Is the machine operating independently of any other generator, supplying a load or loads that are isolated from a larger grid and other machines?
What was the frequency of the system the machine was supplying at the time of the incident? What was the generator frequency at the time of the incident?
What was the system voltage at the time of the incident?
This is a steam turbine, with a boiler probably burning some kind of coal or wood products; was there any other problems with the steam turbine or steam supply which occurred before this 86B lockout relay was actuated?
Based on the information provided, there's just not much we can say. Occasionally, there are a couple of people who respond to threads/questions on Control.com who have some very unique experience and might be able to offer some assistance.
