GE Industrial Solutions MicroVersaTrip PM - Manual (Page 27)

MicroVersaTrip Plus™ and MicroVersaTrip PM™ Trip Units
Chapter 2. Setup Mode
17
Figure 14. Trip Unit display for short-time pickup coupled with
long-time pickup.
The time-current curve for short-time pickup is
shown in Figure 15.
Figure 15. Time-current curve illustrating short-time pickup.
Short-Time Delay
The Trip Unit display for short-time delay is shown
in Figure 16. This function delays the breaker trip on
a short-time trip. The choices of time-delay bands
are listed in Table 12. The delay with
I2T IN is for a
current of 600% of xLT at the lower limit of the
band. The delay with I2T OUT is for the lower limit of
each band.
On ANSI Trip Units ordered with the user-selectable,
switchable instantaneous overcurrent and ground-
fault option, “X,” an additional value of
OFF appears
at the end of the delay band settings. Choosing OFF
disables short-time protection. The short-time OFF
band is interlocked with instantaneous pickup, so
that only one function can be turned off at a time.
The I2T OUT function, illustrated in Figure 17, estab-
lishes a constant time delay. I2T IN biases the delay
with a constant slope, as shown in Figure 18.
Figure 16. Trip Unit display for short-time delay.
B B B Baa a an n n nd d d d T T T Tiiiim m m meee e D D D Deee ellllaa a ayyyyssss,,,, sssseee eccc c
1 0.10
2 0.21
3 0.35
Table 12. Lower-limit delays for I2T OUT short-time delay bands.
Figure 17. Time-current curve for short-time delay with I2T OUT .
Figure 18. Time-current curve for short-time delay with I2T IN .