86
NVA100X-D - Manual - 02 - 2016
FUNCTION CHARACTERISTICS
The fi rst threshold trip (
U
<) may be inhibited by start of the second threshold (
U
<<) by setting
ON
the U< Disabling by U<< start (
U<disbyU<<
) parameter available inside the
Set \ Profi le A(or B) \
Undervoltage-27 \ U<< Element \ Setpoints
menu.
User can disable both 27 protection thresholds from the keyboard. During this command, the trip
output relay (U <and / or U << thresholds) are forced to reset state, the message “27 Disabled” is
displayed and all LEDs blink until the end of the command.
Breaker failure (BF)
All undervoltage elements can produce the Breaker Failure output if the
U< BF
and
U<< BF
pa-
rameters are set to
ON.
The parameters are available inside the
Set \ Profi le A(or B) \ Undervoltage
- 27 \
U< Element
(
U<< Element) \ Setpoints
menus.
[1]
VT monitoring (74VT)
Both the protection elements are blocked off whenever the VT supervision function is active, so
that no unwanted trip can arise if any fault on the VTs secondary circuits (break, fuse trip, etc)
are detect;
[2]
the Block functions enable from 74VT parameter
74VT-BK-EN
is available inside the
Set \ VT supervision -74VT.
For every of the two elements the logic block is available:
Logical block (Block1)
If the
U<BLK1
and/or
U<<BLK1
enabling parameters are set to
ON
and a binary input is designed
for logical block (Block1), the protection is blocked off whenever the given input is active.
The trip timer is held in reset condition, so the operate time counting starts when the input block goes
down.
[3]
The enabling parameters are available inside the
Set \ Profi le A(or B) \ Undervoltage - 27 \
U< Element
(
U<< Element) \ Setpoints
menus, while the
Block1
function must be assigned to the
selected binary input inside the
Set \ Board1(2) inputs \ Binary input IN1-1...INx-x
menus.
All parameters can be set separately for A and B setting profi les
Note 1 The common settings concerning the Breaker failure protection are adjustable inside the
Breaker Failure - BF
menu.
Note 2 The exhaustive treatment of the VT supervision function may be found in the “VT supervision - 74VT” paragraph inside
CONTROL AND MONI-
TORING
section.
Note 3 The exhaustive treatment of the logical block (Block 1) function may be found in the “Logic Block” paragraph inside
CONTROL AND MONITOR-
ING
section.
all-F27.ai
U< Element
U<< Element
MMI
Start U<<
Start U<<
Start U<
Trip U<
Trip U<<
&
U< disbyU<<
&
U< inhibition
t
U< def
t
U< inv
U<
def
t
U<< def
U<<
def
U<
inv
U< Curve
U< Enable
State
Block1
BLK1U<
&
U<BLK1
Start U<
&
Block1
BLK1U<<
&
U<<BLK1
Start U<<
&
U<BF
Trip U<
&
U<BF
U<<BF
Trip U<<
&
U<<BF
U
74VT
&
U
74VT
AND
U
12
,
U
23
,
U
31
U
U
L1
,
U
L2
,
U
L3
OR
Common configuration
Utype27
Disable 27-37-81 functions by operator
Logic27
General logic diagram of the undervoltage elements - 27
all-F27.ai
U< Element
U<< Element
MMI
Start U<<
Start U<<
Start U<
Trip U<
Trip U<<
&
U< disbyU<<
&
U< inhibition
t
U< def
t
U< inv
U<
def
t
U<< def
U<<
def
U<
inv
U< Curve
U< Enable
State
Block1
BLK1U<
&
U<BLK1
Start U<
&
Block1
BLK1U<<
&
U<<BLK1
Start U<<
&
U<BF
Trip U<
&
U<BF
U<<BF
Trip U<<
&
U<<BF
U
74VT
&
U
74VT
AND
U
12
,
U
23
,
U
31
U
U
L1
,
U
L2
,
U
L3
OR
Common configuration
Utype27
Disable 27-37-81 functions by operator
Logic27
General logic diagram of the undervoltage elements - 27
