GE 469 Instruction Manual page 225

7 TESTING
Symmetrical component analysis of vectors using the mathematical vector convention yields a ratio of negative sequence
current to positive sequence current as shown:
Given the values in the figure above, we have:
∠ (
I
780 0° 1 120°
+
2
--- - = ------------------------------------------------------------------------------------------------------------------------------------------------------------------- -
I
∠ (
780 0° 1 120°
+
1
∠
780 0° 1000 127°
+
= ----------------------------------------------------------------------------------------------- -
∠
780 0° 1000 7°
+
If FLA = 1000, then:
I
and since = 926.7 A 1000
avg
The 469 specification for unbalance accuracy is ±2%. Perform the steps below to verify accuracy.
1. Alter the following setpoints:
Õ
S2 SYSTEM SETUP
Õ
S2 SYSTEM SETUP
2. Inject the values shown in the table below and verify accuracy of the measured values. View the measured values in:
Õ
A2 METERING DATA CURRENT METERING
INJECTED CURRENT
1 A UNIT
Ia = 0.78 A ∠0°
Ib = 1 A ∠247°
Ic = 1 A ∠113°
Ia = 1.56 A ∠0°
Ib = 2 A ∠247°
Ic = 2 A ∠113°
Ia = 0.39 A ∠0°
Ib = 0.5 A ∠247°
Ic = 0.5 A ∠113°
GE Multilin
Courtesy of NationalSwitchgear.com
1
2
( )
-- - I a I aI
+ +
I
a b c
3
2
where a
--- - = ------------------------------------------- -
I 1
2
( )
1
-- - I aI a I
+ +
a b c
3
2
∠ ) ( ∠ ) ( ∠
1000 113° 1 120°
– +
∠ ) 1000 ( ∠ ) ( ∠
113° 1 120°
– +
∠ ∠
1000 233° 780 601.8
+
= -------------------------------------------------------------------------------------------------- -
∠ ∠
1000 353° 780
+
780 + 1000
------------------------------------------------ - A
I =
avg
<
= FLA the 469 unbalance is:
469 Unbalance 0.1532
= –
Õ
CURRENT SENSING PHASE CT PRIMARY:
Õ×
CURRENT SENSING MOTOR FULL LOAD AMPS FLA:
EXPECTED UNBALANCE
5 A UNIT
Ia = 3.9 A ∠0°
Ib = 5 A ∠247°
Ic = 5 A ∠113°
Ia = 7.8 A ∠0°
Ib = 10 A ∠247°
Ic = 10 A ∠113°
Ia = 1.95 A ∠0°
Ib = 2.5 A ∠247°
Ic = 2.5 A ∠113°
469 Motor Management Relay
7.3 ADDITIONAL FUNCTIONAL TESTING
∠
1 120° 0.5 j 0.886
= = – +
) 1000 133° ( ∠ )
2
) ( ∠ )
1000 133°
j 798.6 601.8 j 798.6
– + – –
992.5 j 121.9 992.5 j 121.9
+ + + +
+ 1000
= 926.7 A
3
926.7
× ×
-------------- - 100% 14.2%
=
1000
"1000 A"
"1000 A"
MEASURED UNBALANCE LEVEL
LEVEL
14%
15%
7%
(EQ 7.2)
(EQ 7.3)
423.6
–
0.1532
= ----------------- - = –
2765
(EQ 7.4)
(EQ 7.5)
7
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