Siemens ISGS SG8158-00 - Manual (Page 27)

Protective Function Configuration
Siemens Energy & Automation, Inc. 21
5 Protective Function Configuration
5.1 Overview
This chapter explains how to set the parameters for the
protective functions of the ISGS relay.
Password
All parameter changes require a password. Refer to
Section 3.3 on how to enter your password. Viewing
parameter settings does not require a password.
Note: The ISGS relay is not password protected
when making parameter changes through
Wisdom software.
Configuration Steps
Perform parameter changes using steps 1 through 9 of the
standard operating procedures described in Section 3.5.
Parameter Sets
Many protective functions can be set to two different param-
eter sets—set A and set B. These functions are indicated by
the letter A or B preceding the address block number. Alter-
nate sets are useful for seasonal settings or for special oper-
ating periods. Either set can be selected (in address block
7100) to be the active set that controls the relay operation.
The parameters for both sets are entered in the relevant
address blocks. Waveform capture buffer settings apply to
both parameter sets. Unless you do not desire an alternate
set, configure both sets when configuring the relay.
Note: The settings for parameter sets A and B are
entered in the address block. However, the
parameter set which the ISGS relay is
actively using is selected at address block
7100. Refer to Section 6.11 for discussion
of parameter sets.
Actions on Pickup or Trip
Protective functions can be set to have actions occur on
pickup or on trip. Binary outputs can be set to be actuated
on pickup of a protective function. A protective function is set
to trip a breaker by assigning the trip contact that is con-
nected to the breaker (default is Trip 1). Binary outputs can
also be assigned to trip a breaker. It is possible, however to
have a protective function enabled and not assigned to any
output. Events and their sequences are entered in the trip log
as usual, but the breaker will not be affected. This setting is
useful for monitoring and alarming without tripping, and for
waveform capture. For more information on the control of
inputs and outputs, refer to Chapter 6.
Pickup
When testing induction disk relays, an established practice is
to set the pickup value to 1.0 A of secondary CT output. The
time overcurrent curves will show a pickup, but the relay will
not trip in a predefined repeatable manner until it reaches 1.3
to 1.5 A. With numerical relays like the ISGS, however, a sus-
tained pickup indication means definite operation. To
account for measurement inaccuracies, and to guarantee
that the relay will never trip at 100% of pickup or below, the
pickup point is set at 106% of the pickup setting to avoid any
unintended nuisance trips.
Neutral or Ground
The availability of protective functions for neutral or ground
depends on how the external CTs are connected. If a ground
or zero-sequence CT is used and connected to the fourth
internal CT, the ground or neutral protective function is a
ground function. If the fourth CT is connected in the common
return of the other three internal CTs (residual), the function is
indicated as being neutral. There does not need to be an
explicit selection of neutral or ground.
Custom Curve
The custom curve is one user-defined curve that can be
used by one or more protective functions that have the cus-
tom curve option in the curve list.
Wisdom Software
While the ISGS relay protective functions can be completely
configured manually using the LCD and the keypad, Wisdom
software allows faster and easier configuration when it is
used on a PC connected to either data port. For data port
connections refer to Section 2.5.
5.2 Instantaneous Phase Overcurrent (50)
The Instantaneous Phase Overcurrent function consists of a
phase instantaneous overcurrent function and an adjustable
delay. This function begins timing when any individual phase
current exceeds the pickup at 100% of set pickup point and
drops out at 95% of the pickup point.
The function can be enabled or disabled (1501).
The range of the pickup value (1502) depends on the sec-
ondary phase CT rating (1 A or 5 A), and the value is in sec-
ondary amperes.
The time delay (1504) represents the time between pickup
and trip and can be adjusted from 0 to 60 seconds in steps
of 0.1 second. If the function remains in pickup for longer
than the time delay, the function causes a trip. The delay can
also be set to infinity so that the function never times out.
Each of the two waveform capture buffers (1510 and 1511)
can be independently programmed to freeze snapshots on
pickup or trip.
The function is able to actuate any binary output contact on
pickup, and any trip or binary output contact on trip.
A1500 Instantaneous Phase Overcurrent (50)
Address Parameter Option
1501 Function Enabled or Disabled
1502 Pickup 5 A CTs: 1-120 A
1 A CTs: 0.2-24 A
(0.1 A steps)
1504 Time Delay 0-60 s (0.01 s steps)
1510 Freeze Wfm1 on Pickup, on Trip, or None
1511 Freeze Wfm2 on Pickup, on Trip, or None
1512 Blocked by None, 50HS & 50HSN, 50 HSN,
or 50HS
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