GE C70 Instruction Manual page 148

5.2 PRODUCT SETUP
• LANGUAGE: This setting selects the language used to display settings, actual values, and targets. The range is
dependent on the order code of the relay.
• FLASH MESSAGE TIME: Flash messages are status, warning, error, or information messages displayed for several
seconds in response to certain key presses during setting programming. These messages override any normal mes-
sages. The duration of a flash message on the display can be changed to accommodate different reading rates.
• DEFAULT MESSAGE TIMEOUT: If the keypad is inactive for a period of time, the relay automatically reverts to a
default message. The inactivity time is modified via this setting to ensure messages remain on the screen long enough
during programming or reading of actual values.
• DEFAULT MESSAGE INTENSITY: To extend phosphor life in the vacuum fluorescent display, the brightness can be
attenuated during default message display. During keypad interrogation, the display always operates at full brightness.
• SCREEN SAVER FEATURE and SCREEN SAVER WAIT TIME: These settings are only visible if the C70 has a liquid
crystal display (LCD) and control its backlighting. When the
is turned off after the
have been pressed and no target messages are active. When a keypress occurs or a target becomes active, the LCD
backlighting is turned on.
• CURRENT CUT-OFF LEVEL: This setting modifies the current cut-off threshold. Very low currents (1 to 2% of the
rated value) are very susceptible to noise. Some customers prefer very low currents to display as zero, while others
prefer the current be displayed even when the value reflects noise rather than the actual signal. The C70 applies a cut-
off value to the magnitudes and angles of the measured currents. If the magnitude is below the cut-off level, it is substi-
tuted with zero. This applies to phase and ground current phasors as well as true RMS values and symmetrical compo-
nents. The cut-off operation applies to quantities used for metering, protection, and control, as well as those used by
communications protocols. Note that the cut-off level for the sensitive ground input is 10 times lower that the
setting value. Raw current samples available via oscillography are not subject to cut-off.
CUT-OFF LEVEL
5
• VOLTAGE CUT-OFF LEVEL: This setting modifies the voltage cut-off threshold. Very low secondary voltage measure-
ments (at the fractional volt level) can be affected by noise. Some customers prefer these low voltages to be displayed
as zero, while others prefer the voltage to be displayed even when the value reflects noise rather than the actual sig-
nal. The C70 applies a cut-off value to the magnitudes and angles of the measured voltages. If the magnitude is below
the cut-off level, it is substituted with zero. This operation applies to phase and auxiliary voltages, and symmetrical
components. The cut-off operation applies to quantities used for metering, protection, and control, as well as those
used by communications protocols. Raw samples of the voltages available via oscillography are not subject cut-off.
The
CURRENT CUT-OFF LEVEL
power cut-off level is calculated as shown below. For Delta connections:
3-phase power cut-off
For Wye connections:
3-phase power cut-off
per-phase power cut-off
where VT primary = VT secondary  VT ratio and CT primary = CT secondary  CT ratio.
For example, given the following settings:
CURRENT CUT-OFF LEVEL
VOLTAGE CUT-OFF LEVEL
PHASE CT PRIMARY
PHASE VT SECONDARY
: "208.00 : 1"
PHASE VT RATIO
PHASE VT CONNECTION
We have:
CT primary = "100 A", and
VT primary =
PHASE VT SECONDARY
5-24
DEFAULT MESSAGE TIMEOUT
and the
VOLTAGE CUT-OFF LEVEL

3
CURRENT CUT-OFF LEVEL
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- -
=

3
CURRENT CUT-OFF LEVEL
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- -
=
CURRENT CUT-OFF LEVEL
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- -
=
: "0.02 pu"
: "1.0 V"
: "100 A"
: "66.4 V"
: "Delta".
x
PHASE VT RATIO
C70 Capacitor Bank Protection and Control System
SCREEN SAVER FEATURE
followed by the
SCREEN SAVER WAIT TIME
are used to determine the metered power cut-off levels. The

VOLTAGE CUT-OFF LEVEL
VT secondary

VOLTAGE CUT-OFF LEVEL
VT secondary

VOLTAGE CUT-OFF LEVEL
VT secondary
= 66.4 V x 208 = 13811.2 V
5 SETTINGS
is "Enabled", the LCD backlighting
, providing that no keys
CURRENT
 
VT primary CT primary
(EQ 5.3)
 
VT primary CT primary
(EQ 5.4)
 
VT primary CT primary
(EQ 5.5)
GE Multilin