Restrained pickup testing examples, Increasing one input from balance, Restrained pickup testing examples -2 – Basler Electric BE1-87T User Manual
Page 98: Increasing one input from balance -2
5-2
BE1-87T Test Procedures
9171300990 Rev V
Restrained Pickup Testing Examples
Increasing 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) i.e.
I
T
I
T
1
1
2
2
−
slope = the
RESTRAINED PICKUP LEVEL setting (15 to 60)
maximum restraint = larger of I
1
or I
2
in pu i.e.
I
T
or
I
T
1
1
2
2
By increasing the I
1
input current from balance: (The balance current is I
I
T
T
Amps
1
2
1
2
=
×
1)
When:
I
slope
slope
balance
1
0 35
100
1
100
>
−
.
OR
I
T
slope
slope
2
2
0 35
100
1
100
>
−
.
(in pu)
This means the pu restraint current is to the right of the intersection of the slope characteristic with the
0.35 MPU horizontal line (see Figure 1-2).
the minimum trip point is established as:
(Equation 1)
OR
I
I
s
T
T
trip
1
2
1
2
1
min
=
−
×
(in Amps)
(Equation 1a)
2)
When:
the minimum trip point is established as:
(Equation 2)
OR
I
T I
T
trip
1
1
2
2
0 35
min
.
=
+
(in Amps)
(Equation 2a)
unbalance >
(maximum restraint)
or 0.35 pu, whichever is greater
slope
100
I
I
slope
trip min
balance
1
1
1
(100)
=
-
(in pu)
I balance
slope
slope
1
0 35
100
1
100
<
-
(
)
.
(in pu)
(
)
I
I
trip min
balance
1
1
=
+ 0.35 (in pu)