Multilin 469 Motor Management Relay ... - GE Digital Energy

CHAPTER 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:
1
I
-- I
2
---
3 a a
I1 Given the values in the figure above, we have:
2 ( + Ib + aIc) 1
-- I
3 a aIb a 2 = ------------------------------------------ where a =
( + + Ic) 1∠120° = – 0.5 + j0.886
If FLA = 1000, then:
7.3.4 Voltage Phase Reversal Test
I2 ---
I1 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 + j798.6 – 601.8 – j798.6 – 423.6
-------------------------------------------------------------------------------------------- = ----------------
780 + 992.5 + j121.9 + 992.5 – j121.9 2765
= 0.1532
and since Iavg = 926.7 A < 1000 = FLA , the 469 unbalance is:
(EQ 7.2)
(EQ 7.3)
(EQ 7.4)
(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
INJECTED CURRENT EXPECTED
1 A UNIT 5 A UNIT
UNBALANCE
LEVEL
Ia = 0.78 A ∠0°
Ib = 1 A ∠113°
Ic = 1 A ∠247°
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°
I avg
780 + 1000 + 1000
= ---------------------------------------------- A = 926.7 A
3
926.7
469 Unbalance = – 0.1532 × ------------- × 100% =
14.2%
1000
Ia = 3.9 A ∠0°
Ib = 5 A ∠113°
Ic = 5 A ∠247°
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°
MEASURED
UNBALANCE
LEVEL
The 469 can detect voltage phase rotation and protect against phase reversal. To test the
phase reversal element, perform the following steps:
469 MOTOR MANAGEMENT RELAY – INSTRUCTION MANUAL 7–13
14%
15%
7%