GE UR Series C70, Instruction Manual

Page: 321 / 614

GE Multilin C70 Capacitor Bank Protection and Control System 5-197
5 SETTINGS 5.8 INPUTS/OUTPUTS
5
The FlexLogic™ operand response time to the contact input change is equal to the debounce time setting plus up to one
protection pass (variable and depending on system frequency if frequency tracking enabled). If the change of state occurs
just after a protection pass, the recognition is delayed until the subsequent protection pass; that is, by the entire duration of
the protection pass. If the change occurs just prior to a protection pass, the state is recognized immediately. Statistically a
delay of half the protection pass is expected. Owing to the 0.5 ms scan rate, the time resolution for the input contact is
below 1msec.
For example, 8 protection passes per cycle on a 60 Hz system correspond to a protection pass every 2.1 ms. With a con-
tact debounce time setting of 3.0 ms, the FlexLogic™ operand-assert time limits are: 3.0 + 0.0 = 3.0 ms and 3.0 + 2.1 = 5.1
ms. These time limits depend on how soon the protection pass runs after the debouncing time.
Regardless of the contact debounce time setting, the contact input event is time-stamped with a 1
μ
s accuracy using the
time of the first scan corresponding to the new state (mark no. 2 below). Therefore, the time stamp reflects a change in the
DC voltage across the contact input terminals that was not accidental as it was subsequently validated using the debounce
timer. Keep in mind that the associated FlexLogic™ operand is asserted/de-asserted later, after validating the change.
The debounce algorithm is symmetrical: the same procedure and debounce time are used to filter the LOW-HIGH (marks
no.1, 2, 3, and 4 in the figure below) and HIGH-LOW (marks no. 5, 6, 7, and 8 below) transitions.
Figure 5–101: INPUT CONTACT DEBOUNCING MECHANISM AND TIME-STAMPING SAMPLE TIMING
Contact inputs are isolated in groups of four to allow connection of wet contacts from different voltage sources for each
group. The
CONTACT INPUT THRESHOLDS
determine the minimum voltage required to detect a closed contact input. This
value should be selected according to the following criteria: 17 for 24 V sources, 33 for 48 V sources, 84 for 110 to 125 V
sources and 166 for 250 V sources.
For example, to use contact input H5a as a status input from the breaker 52b contact to seal-in the trip relay and record it in
the Event Records menu, make the following settings changes:
CONTACT INPUT H5A ID:
"Breaker Closed (52b)"
CONTACT INPUT H5A EVENTS:
"Enabled"
Note that the 52b contact is closed when the breaker is open and open when the breaker is closed.
842709A1.cdr
D E BOU N C E T I M E
(user sett i ng)
At th i s t i me, the
new ( HI G H )
contact state i s
va li dated
The Fl exLog i c
TM
operand i s go i ng to
be asserted at th i s
protect i on pass
The Fl exLog i c
TM
operand
changes ref l ect i ng the
va li dated contact state
T i me stamp of the f i rst
scan correspond i ng to
the new va li dated state i s
l ogged i n the SO E record
2 1 3
4
D E BOU N C E T I M E
(user sett i ng)
At th i s t i me, the new
(LOW) contact state i s
va li dated
The Fl exLog i c TM
operand i s go i ng to be
de - asserted at th i s
protect i on pass
The Fl exLog i c
TM
operand
changes ref l ect i ng the
va li dated contact state
5
7
8
T i me stamp of the f i rst
scan correspond i ng to the
new va li dated state i s
l ogged i n the SO E record
6
SCA N T I M E
(0 . 5 msec)
PROT E CT I O N PASS
(8 t i mes a cyc l e contro ll ed by the
frequency trac ki ng mechan i sm)
RA
W
C
O
N
TAC
T
STAT
E
F
L
E
X
LOG
I
C
TM
OP
E
RA
N
D
IN
PU
T
VO
L
T
AG
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US E R - PROGRAMMABL E T H R E S H OLD