+ Post New Thread
Results 1 to 6 of 6
  1. #1
    Member level 3
    Points: 443, Level: 4

    Join Date
    Aug 2018
    Posts
    56
    Helped
    0 / 0
    Points
    443
    Level
    4

    Derive relation between time and current in motor protection device

    Dear all,

    I am trying to imperilment The IT - characteristic feature for motor protection device.There are 2C,5C,10C curve feature . can someone suggest me how it can be implemented in C code.

    Is there any example code available.

    https://www.l-3.com/private/ieee/Mot...Principles.pdf

    Is there any equation for setting current and time . which i can easily used for implementation.Click image for larger version. 

Name:	IT_char.jpg 
Views:	7 
Size:	47.6 KB 
ID:	150479

    •   AltAdvertisement

        
       

  2. #2
    Member level 3
    Points: 443, Level: 4

    Join Date
    Aug 2018
    Posts
    56
    Helped
    0 / 0
    Points
    443
    Level
    4

    Re: Derive relation between time and current in motor protection device

    Is there any update on below request

    •   AltAdvertisement

        
       

  3. #3
    Advanced Member level 5
    Points: 12,521, Level: 26
    Achievements:
    7 years registered

    Join Date
    Apr 2010
    Posts
    1,902
    Helped
    405 / 405
    Points
    12,521
    Level
    26

    Re: Derive relation between time and current in motor protection device

    if equation is not available , use lookup table with interpolation.

    •   AltAdvertisement

        
       

  4. #4
    Member level 3
    Points: 443, Level: 4

    Join Date
    Aug 2018
    Posts
    56
    Helped
    0 / 0
    Points
    443
    Level
    4

    Re: Derive relation between time and current in motor protection device

    I find solution for IT characteristic. this sample example given here. need c code

    assume Overload current = 10A(user defined setting)

    Over load current trip time =10s(user defined setting)

    if curve 2C is selected

    calculation are as below The relay should turn on 30% over load trip time i.e 13A
    Trip_Time over_current
    10 10
    9 10.3
    8 10.6
    7 10.9
    6 11.2
    5 11.5
    4 11.8
    3 12.1
    2 12.4
    1 12.7
    0 13

    in code if the Nominal current exceeds overload current these are trip timing for relay. The timing and current will change as per user defined setting. can some one guide me C code.

  5. #5
    Advanced Member level 5
    Points: 12,521, Level: 26
    Achievements:
    7 years registered

    Join Date
    Apr 2010
    Posts
    1,902
    Helped
    405 / 405
    Points
    12,521
    Level
    26

    Re: Derive relation between time and current in motor protection device

    make an array of 'time[] ' with index as "current*10" and initialise with your values.
    from the given 'current' enter the array as 'index' , get the 'time ' value.

    •   AltAdvertisement

        
       

  6. #6
    Super Moderator
    Points: 259,183, Level: 100
    Awards:
    1st Helpful Member

    Join Date
    Jan 2008
    Location
    Bochum, Germany
    Posts
    45,250
    Helped
    13765 / 13765
    Points
    259,183
    Level
    100

    Re: Derive relation between time and current in motor protection device

    How do you determine the trip time for arbitrarily varying currents? Notice that the shown IT characteristic follows a simple I^2 t function.

--[[ ]]--