SEL-487V Data Sheet
Schweitzer Engineering Laboratories, Inc.
6
Voltage Elements
The SEL-487V provides six independent over- and
undervoltage elements with two pickup levels. The first
pickup level is provided with a definite-time delay.
Choose from a wide range of fundamental and rms
operating quantities for the Y and Z terminal voltage
inputs.
shows the voltage inputs available for use
as operating quantities.
Inverse-Time Overvoltage Elements
Six inverse-time overvoltage elements are provided, and
are designed to meet the IEC 60871-1:2005 standard for
maximum allowable overvoltage for capacitor banks in
service. Selectable operating quantities provide
flexibility for the input to the inverse time overvoltage
elements, and the built-in logic tracks overvoltage
duration with respect to operating time.
Frequency Elements
The SEL-487V provides six frequency elements, driven
from either the Y or the Z potential transformers. Any of
the six elements may be configured for over- or under-
frequency. Each frequency element provides a pickup
time delay setting. The frequency elements are
supervised by a programmable undervoltage element.
The undervoltage element can be set to monitor either Y
or Z potential inputs, and will block the assertion of the
81 element when the selected voltage input falls below a
programmable undervoltage supervision threshold.
Current Unbalance
The SEL-487V uses the average three-phase terminal
current on the W current terminals to calculate the
percentage difference between the individual phase
current and the terminal average current. If the
percentage difference is greater than the set pickup value
the phase unbalance element is asserted. To prevent this
element from asserting during fault conditions and after a
terminal circuit breaker has closed, the final terminal
unbalance output (46
n
P) is supervised, using current,
fault detectors, and the open-phase detection logic. The
current unbalance logic is blocked from operating if any
of the following conditions is true:
➤
The mean terminal current is less than 5% or
greater than 200% of I nominal (I
NOM
= 1 A or 5 A)
➤
The FAULT Relay Word is asserted
➤
The circuit breaker has been closed (open phase
detection element has deasserted for a settable
dropout period)
Breaker Failure Protection
Incorporated into the SEL-487V is a full function
breaker failure system. High-speed open-pole detection
logic allows you to set the pickup current below
minimum load for sensitivity without sacrificing high-
speed dropout. Even in cases with delayed current zero in
the secondary of the CT caused by trapped flux, high-
speed detection of circuit breaker opening is achieved.
This feature is essential if breaker failure is initiated on
all circuit breaker trips. A reset of less than one cycle
reduces coordination times, improving stability.
Breaker Flashover Detection
The SEL-487V provides logic to detect a reignition or
restrike (also called flashover) across any one of the three
breaker poles of the W terminal breaker after the breaker
has opened.
The SEL-487V uses rms current measurement and open-
phase detection logic to detect breaker flashover
conditions that may exist during capacitor switching
operations.
Multiple restrike or reignition conditions are typically
indicative of contaminated dielectric material, reduced
breaker contact separation, or an improperly rated breaker.
Thermal Overload Protection
The SEL-487V provides three independent IEC thermal
models for thermal overload protection of a variety of
devices, including in-line reactors used to limit capacitor
bank switching transients.
Ambient temperature measurements for the thermal
model are provided using the SEL-2600 RTD Module.
Loss-of-Potential (LOP) Logic
Supervises Voltage Elements
The SEL-487V includes logic to detect a loss-of-
potential (LOP) caused by failures such as blown fuses,
which can cause an incorrect operation in voltage
elements. Configure the LOP logic to block voltage
differential elements under these conditions. The logic
checks for a sudden change in positive-sequence voltage
Table 3
Voltage Element Operating Quantities
Analog Quantity
Description
VA, VB, VC
L–N Phase Voltage
VNMAX, VNMIN
Neutral Voltage Min/Max
VAB, VBC, VCA
L–L Phase Voltage
VA–VN
a
, VB–VN
a
, VC–VN
a
a
Fundamental quantities only.
Phase Voltage with Neutral
Voltage Subtracted
VPMAX, VPMIN
Phase Voltage Min/Max
V1
a
, 3V2
a
, 3V0
a
Positive-, Negative-, Zero-
Sequence