1.4
SEL-587Z Instruction Manual Date Code 20020903
Introduction and Specifications
SEL-587Z Functions
SEL-587Z Functions
Figure 1.3 Protection Functions.
Differential
Protection
Three independent high-impedance elements provide security for through
faults, even during deep CT saturation conditions, yet provide fast clearance
for in-zone faults. Built-in, per-phase metal oxide varistors (MOV) protect the
CT wiring and relay against high-voltage surges during in-zone faults.
Because the elements are independent, use single elements for sensitive
restricted earth fault protection on grounded wye-connected transformer
windings.
Overcurrent
Protection
Three independent sets of overcurrent elements provide the following:
Instantaneous phase and residual overcurrent elements
Definite-time phase, residual, and negative-sequence
overcurrent elements
Inverse-time phase, residual, and negative-sequence
overcurrent elements
Overcurrent element pickup settings and operating characteristics are
independent from the differential element settings. When you use the
SEL-587Z for transformer protection, the instantaneous overcurrent elements
provide phase and ground overcurrent protection for bushing faults, while the
time-overcurrent elements provide phase and ground protection for
coordinating with other system protection.
SEL-587Z Relay
52-1
3
3
i2130d 09APR2002
50
P
G
Q
P
G
Q
51
Inverse Time-Overcurrent
• Phase (Maximum)
• Neutral
• Negative Sequence
Instantaneous Overcurrent
• Phase (Maximum)
• Neutral
• Negative Sequence
Three-Phase
High-Impedance
Differential Elements
Stabilizing
Resistor
87
• SELOGIC
®
Control Equations
• Event Reports
• Sequential Events Recorder
• SEL ASCII, SEL Fast Messages,
Modbus
®
, and Distributed Port
Switch Communications
• Remote and Local Control
Switches
•
Differential, Phase, Negative
Sequence, and Ground Metering
• Built-in Per-Phase Resistors and
MOVs
• Peak and Maximum Demand
Metering
52-2
52-3
52-4
52
m
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