What do the protection function numbers mean?
In single line diagrams and other documents depicting protection details you can see various numbers. These numbers are also called ‘ANSI codes’ as they are defined in the ANSI/IEEE standard. What do the protection function numbers mean?
You have surely seen them: the mysterious numbers in various system drawings and schematics representing the protection functions. Well, they are not that mysterious at all. And due to their wide use it is surely good to have a bit of an overview.
The standard defining the protection function numbers is IEEE Standard C37.2 for Electrical Power System Device Function Numbers, Acronyms, and Contact Designations [1].
99 numbers are defined (including few reserved ones) in the standard. In this post we just limit ourselves to few of them commonly used also in drive systems:
- Device number 3 – Checking or interlocking relay
- Device number 7 – Rate of change relay
- Device number 12 – Overspeed device
- Device number 14 – Underspeed device
- Device number 15 – Speed or frequency matching device
- Device number 21 – Distance relay
- Device number 23 – Temperature control device
- Device number 24 – Volts per Hertz relay
- Device number 27 – Undervoltage relay
- Device number 49 – Machine or transformer thermal relay
- Device number 50 – Instantaneous overcurrent relay
- Device number 51 – Inverse time overcurrent relay
- Device number 53 – Field excitation relay
- Device number 59 – Overvoltage relay
- Device number 60 – Voltage or current balance relay
- Device number 64 – Ground detector relay
- Device number 81 – Frequency relay
- Device number 87 – Differential protective relay
Do you want to know more about protection in variable speed drive systems and other related topics? Purchase our premium subscription or join one of our webinars.
References
[1] IEEE Std. C37.2™-2008 Electrical Power System Device Function Numbers, Acronyms, and Contact Designations, New York, USA, October 2008
[2] Short circuit currents in variable speed drive systems, https://mb-drive-services.com/short-circuit-currents-in-variable-speed-drive-systems/
Rental of converter transformer
In the event of:
- Failure of original transformer
- Specific test campaign
- Other temporary use
In need? Contact us.
