CHAPTER 5: SETTINGS
GROUPED ELEMENTS
M60 MOTOR PROTECTION SYSTEM – INSTRUCTION MANUAL
5-251
5
Table 5-34: Quantities for "calculated 3I0" configuration
Table 5-35: Quantities for "measured IG" configuration
where:
ECA = element characteristic angle
IG = ground current
Z_offset is the offset impedance, for which magnitude is the OFFSET setting and angle is the FWD ECA
When
NEUTRAL DIR OC1 POL VOLT
is set to “Measured VX,” one-third of this voltage is used in place of V_0. The following
figure explains the usage of the voltage polarized directional unit of the element.
The figure shows the voltage-polarized phase angle comparator characteristics for a phase A to ground fault, with:
•
ECA = 90° (element characteristic angle = centerline of operating characteristic)
•
FWD LA = 80° (forward limit angle = the ± angular limit with the ECA for operation)
•
REV LA = 80° (reverse limit angle = the ± angular limit with the ECA for operation)
Take the bias into account when using the neutral directional overcurrent element to directionalize other protection
elements.
Directional unit
Overcurrent unit
Polarizing mode
Direction
Compared phasors
Voltage
Forward
–V_0 + Z_offset
×
I_0
I_0
×
1
∠
ECA
I
op
= 3
×
(|I_0| – K
×
|I_1|) if |I
1
| > 0.8 pu
I
op
= 3
×
(|I_0|) if |I
1
|
≤
0.8 pu
Reverse
–V_0 + Z_offset
×
I_0
–I_0
×
1
∠
ECA
Current
Forward
IG
I_0
Reverse
IG
–I_0
Dual, Dual-V, Dual-I
Forward
–V_0 + Z_offset
×
I_0
I_0
×
1
∠
ECA
or
IG
I_0
Reverse
–V_0 + Z_offset
×
I_0
–I_0
×
1
∠
ECA
or
IG
–I_0
Directional unit
Overcurrent unit
Polarizing mode
Direction
Compared phasors
Voltage
Forward
–V_0 + Z_offset
×
IG/3
IG
×
1
∠
ECA
I
op
= |IG|
Reverse
–V_0 + Z_offset
×
IG/3
–IG
×
1
∠
ECA
Summary of Contents for M60
Page 9: ...TABLE OF CONTENTS M60 MOTOR PROTECTION SYSTEM INSTRUCTION MANUAL ix INDEX ...
Page 10: ...x M60 MOTOR PROTECTION SYSTEM INSTRUCTION MANUAL TABLE OF CONTENTS ...
Page 552: ...5 344 M60 MOTOR PROTECTION SYSTEM INSTRUCTION MANUAL TESTING CHAPTER 5 SETTINGS 5 ...
Page 660: ...iv M60 MOTOR PROTECTION SYSTEM INSTRUCTION MANUAL ABBREVIATIONS ...