Decreasing one input from balance, Decreasing one input from balance -4 – Basler Electric BE1-87T User Manual
Page 100
5-4
BE1-87T Test Procedures
9171300990 Rev V
Check:
Therefore: Use Equation 1 or 1a.
From Figure 1-2 (the percentage restraint characteristic of the BE1-87T at 15% slope), the minimum
current where trip occurs is:
In terms of current, the trip current is:
Using Equation 1a:
I
trip
1
114
1 015
2
38
7 06
min
.
.
.
.
=
−
×
=
A
Decreasing One Input from Balance
The formula to determine the unbalance value at which the restrained trip occurs is:
Where:
unbalance - absolute value of I
1
- I
2
in per unit (pu)
slope = the RESTRAINED PICKUP LEVEL setting (15 to 60)
maximum restraint = larger of I
1
or I
2
in pu =I
r
By decreasing the I
2
input current from balance:
The balance current is
I
I
T
T
2
1
2
1
=
×
1)
When:
I
slope
balance
2
0 35
100
>
.
(in pu)
OR
I
T
slope
1
1
0 35
100
>
.
the value of I
2 trip max.
is defined as:
(Equation 3)
I balance
slope
slope
1
0.35
100
1
100
< >
-
(in pu)
>
3 1.983
(
)
(
)
3 < >
0.35
0.15
1 - (0.15)
)
(
I trip
1
1
15
3 pu
0
3.53 pu
= -
=
.
I trip
1
3.53 pu tap
= (3.53) (2.0)
= 7.06 A 6% 100 mA
=
x
±
±
unbalance
(maximum restraint)
or 0.35 pu, whichever is greater
>
slope
100
I
I
slope
trip
balance
2
2
1
100
=
-
)
(in pu)
(