Mitsubishi Electric AE-SW Series Instruction Manual page 31

< Electronic trip relay setting example >
Calculation method for the setting value is explained using the example of the AE1600-SW 1600A WS1G1 relay.
Ir=0.8×In
=0.8×1600A
=1280A
Iu=0.9×Ir
=0.9×1280A
=1152A
Isd=3×Ir
=3×1280A
=3840A
Ig=0.1×In
=0.1×1600A
=160A
Ip=0.8×Iu
=0.8×1152A
=921.6A
In=1600A
Table 31 Current value and operating time by setting value
In (CT rating) = 1600 A
Ir = 1280 A
Iu = 1152 A
T = 100 sec. ± 20% (at 2304 A)
L
Isd = 3840 A ± 15%
Tsd = 0.3 sec. ± 20% (at 5760 A)
Sealing
hole
Fig. 31-2
Ii = 15360 A ± 15%
Ip = 921.6 A ± 10%
Tp = 50 sec. ± 20% (at 2304 A)
Ig = 160 A ± 20%
Tg = 0.8 sec. (at 240 A) ± 20%
−
< Relay sealing >
When sealing is required, use the sealing hole located on top of the ETR cover. (Fig. 31-2)
Ii=12×Ir
=12×1280A
=15360A
T = 100 sec.
L
Current twice the amount of Iu
= operating time at
1152 × 2 = 2304 A
Tsd = 0.3 sec.
Current 1.5 times of Isd
= operating time at
3840 × 1.5 = 5760 A
Tg = 0.8 sec.
Current 1.5 times of Ig
= operating time at
160 × 1.5 = 240 A
Tp = 1/2T
L
At 2304 A,
1/2 of T
L
100 × 0.5 = 50 sec.
Fig. 31-1
In = Rated current (CT rating)
Ir = Rated current setting
Iu = Uninterrupted current
T = LTD time
L
Isd = STD pick-up current
Tsd = STD time
Ii = INST/MCR pick-up
current
Ip = Pre-alarm current
Ig = Ground fault pick-up current
Tg = Ground fault operating time
E-31