GE Masoneilan 469 Series, Instruction Manual

Page: 311 / 348

CHAPTER 7: TESTING
469 MOTOR MANAGEMENT RELAY – INSTRUCTION MANUAL 7–13
Symmetrical component analysis of vectors using the mathematical vector convention
yields a ratio of negative sequence current to positive sequence current as shown:
(EQ 7.2)
Given the values in the figure above, we have:
(EQ 7.3)
If FLA = 1000, then:
(EQ 7.4)
and since , the 469 unbalance is:
(EQ 7.5)
The 469 specification for unbalance accuracy is ± 2%. Perform the steps below to verify
accuracy.

Alter the following settings:
S2 SYSTEM SETUP

CURRENT SENSING

PHASE CT PRIMARY:
“1000 A”
S2 SYSTEM SETUP

CURRENT SENSING

MOTOR FULL LOAD AMPS FLA:
“1000 A”
 Inject the values shown in the table below.
 Verify accuracy of the measured values.
 View the measured values in:
A2 METERING DATA

CURRENT METERING
7.3.4 Voltage Phase Reversal Test
The 469 can detect voltage phase rotation and protect against phase reversal. To test the
phase reversal element, perform the following steps:
INJECTED CURRENT EXPECTED
UNBALANCE
LEVEL
MEASURED
UNBALANCE
LEVEL
1 A UNIT 5 A UNIT
Ia = 0.78 A
∠
0
°
Ib = 1 A ∠ 113 °
Ic = 1 A ∠ 247 °
Ia = 3.9 A
∠
0
°
Ib = 5 A ∠ 113 °
Ic = 5 A ∠ 247 °
14%
Ia = 1.56 A ∠ 0 °
Ib = 2 A ∠ 247 °
Ic = 2 A ∠ 113 °
Ia = 7.8 A ∠ 0 °
Ib = 10 A ∠ 247 °
Ic = 10 A ∠ 113 °
15%
Ia = 0.39 A ∠ 0 °
Ib = 0.5 A ∠ 247 °
Ic = 0.5 A ∠ 113 °
Ia = 1.95 A ∠ 0 °
Ib = 2.5 A ∠ 247 °
Ic = 2.5 A ∠ 113 °
7%
I
2
I
1
----
1
3
---
I
a
a
2
I
b
aI
c
+ +
( )
1
3
---
I
a
aI
b
a
2
I
c
+ +
( )
------------------------------------------- =
where a 1 120 ° ∠ 0.5
–
j 0.886
+ = =
I
2
I
1
----
780 0 ° ∠ 1 120 ° ∠ ( )
2
1000 113 °
–
∠ ( ) 1 120 ° ∠ ( ) 1000 113 ° ∠ ( )
+ +
780 0 ° ∠ 1 120 ° ∠ ( ) 1000 113 °
–
∠ ( ) 1 120 ° ∠ ( )
2
1000 113 ° ∠ ( )
+ +
---------------------------------------------------------------------------------------------------------------------------------------------------------------- =
780 0
° ∠
1000 127
° ∠
1000 233
° ∠
+ +
780 0 ° ∠ 1000 7 ° ∠ 1000 353 ° ∠
+ +
---------------------------------------------------------------------------------------------
=
780 601.8
–
j 798.6 601.8
–
j 798.6
– +
780 992.5 j 121.9 992.5 j 121.9
– + + +
---------------------------------------------------------------------------------------------
423.6
–
2765
-----------------
= =
0.1532
=
I
avg
780 1000 1000
+ +
3
-----------------------------------------------
A 926.7 A
= =
I
avg
926.7 A 1000 < FLA
= =
469 Unbalance 0.1532
–
926.7
1000
-------------
100% × × 14.2%
= =