*(.%
37
INSTANTANEOUS UNIT
The Instantaneous unit is designed
similarly to a hinged armature
instantaneous unit. The instantaneous
unit will react differently depending on
how the signal is applied. If the signal is
applied suddenly with no prefault
current, the operating time will be
longer. If a prefault current is applied
prior to the fault the operating time will
be shorter. The following test
determines that the instantaneous unit
is working correctly and confirms the
operating time for faults applied with no
prefault current.
Connect the relay as shown in figure 25
or 26, Set the instantaneous unit pickup
to 2 Amps (5Amp rated relay) or
0.4Amps (1Amp rated relay) with a zero
IOC delay setting. Apply 6 Amps (5Amp
rated relay) or 1.2 Amps (1 Amp rated
relay) and measure the operating time.
The operating time should be between
32ms and 46ms. This time is subject to
dependent on the multiple of pickup
current and the fault incidence angle. A
graph of how the instantaneous unit
varies as a function of input current is
provided in this book for reference,
figure 16A.
Summary of Contents for DIAC
Page 29: ...28 FIGURE 18 DIAC and DSFC External Internal Connections...
Page 30: ...29 FIGURE 19 DIFC External Internal Connections...
Page 31: ...30 FIGURE 20 DIAC Panel Mounting and Drilling...
Page 32: ...31 FIGURE 21 DIFC Panel Mounting and Drilling...
Page 33: ...32 FIGURE 21A SURFACE MOUNTING DIFC...
Page 34: ...33 FIGURE 22 DSFC Panel Mounting and Drilling...
Page 42: ...41 FIGURE 27 9819647 8919648 DIAC Front and Rear Views...
Page 43: ...42 FIGURE 28 8919652 8919653 DIFC Front and Rear Views...
Page 44: ...43 FIGURE 29 8919632 8919661 DSFC Front and Rear Views...