13
3
1 2 3
Parameters a and b can take on the following
values according to the curve selected.
• Normal inverse time-delay curve (NI):
a = 0.02 b = 0.14.
• Very inverse time-delay curve (VI):
a = 1 b = 13.5.
• Extremely inverse time-delay curve EI):
a = 2 b = 80.
Selection of t> trip time
The trip time of the protection is adjusted by using
the Dip Switches as shown in the figure.
By means of the Dip Switches, the value of K is set
which, when replaced in the previous relation-
ships, determines trip time t>.
The following settings are possible:
• 16 trip times (t>),
(K = 0.1...1.6 with steps of 0.1)
0.1 0.2 0.3 0.4 0.5
0.6 0.7 0.8 0.9 1.0
1.1 1.2 1.3 1.4 1.5 1.6
Caption
1 Dip Switch for setting the trip threshold of protection
I>
2 Dip Switch for setting timing K of protection I>
3 Dip Switch for selecting the type of curve for
protection I>:
• DT curve with definite time
•NI curve with normal inverse time
•VI curve with very inverse time
•EI curve with extremely inverse time.
Protection against instantaneous or
delayed short-circuit (50)
This function makes a family of definite adjustable
time curves available, indicated by the symbol I>>.
The corresponding trip time is indicated by the
symbol t>>.
Start of timing is signalled by the ALARM LED
lighting up, whereas circuit-breaker opening is
signalled on the front by the magnetic flag I> I>>,
turned to the yellow position. To reset signalling,
the FLAG RESET pushbutton on the front of the
release must be pressed, ensuring one of the
following conditions:
a) 24 Vdc auxiliary voltage present (display lit);
b) primary circulating current higher than 0.2 x In
(display lit with indication of the circulating
current);
c) application of the TT2 unit to the TEST connec-
tor on the front of the release (optional acces-
sory).
Selection of I>> threshold value
Setting the I>> threshold is carried out by working
on the Dip Switches as shown in the figure below.
The sum of the values selected represents the
multiple of I> and corresponds to threshold I>>.
N.B. Even if protection I> is OFF, the first Dip Switch
takes on the value 0.2.
The following settings are possible:
• 16 threshold current values (I>>)
2.5 3.5 4.5 5.5
7.5 8.5 9.5 10.5
12 13 14 15
17 18 19 20 x I>
OFF
To Next Page
Loading...
