Micrologic SE 1

[Vov4agius]

In Micrologic specification inverse characteristic for long-time overcurrent is represented by function I2t. All tripping curves for Micrologic illustrated on logarithmic scale. If i am not mistaken on logarithmic scale function I2t must be linear, but in Micrologic specification it does not linear. Could anyone explain please why this function I2t on logarithmic scale is not linear?

 

[dpc]

The I2T function is simply a modification of the short-time trip function which is normally a definite time delay (I2t OFF). It only changes the short-time trip function. The main benefit of the I2t ON setting is to better coordinate with downstream fuses. Turning it on can increase arc-flash duration and incident energy. It's basically a straight diagonal line over the applicable range of current. This looks pretty much like everyone's I2t function. Regardless, the manufacturer's published TCC is what you have to go by.