27
26
NON setting and fail-safe feature
z
NON setting
Setting a trip pickup current function to NON allows you to render
the corresponding protection function inoperative.
Functions having the NON option include LT, ST, INST/MCR,
and GF.
Appropriate NON setting will be a useful means for optimum
selectivity.
x
Fail-safe feature
The OCR has a fail-safe mechanism in case protection functions
are improperly set to NON.
• If the ST and INST trip pickup current functions are both set
to NON, the fail-safe mechanism will activate the INST trip
function to trip the ACB when a fault current equal to or more
than 16 times the rated current [
I
n
] flows through the ACB.
• If the ST and MCR trip pickup current functions are both set
to NON, the fail safe mechanism will activate the ST delay
trip function to trip the ACB when a fault current equal to or
more than 10 times (5 times for generator protection) the rated
current [
I
n
] flows through the ACB.
Specifications
4
r
Adjustable pre-trip alarm function PTA
The pre-trip alarm function provides an alarm signal via the
alarm contact (1a-contact) when the load current exceeding a
predetermined value lasts for a predetermined time. A 2-chan-
nel pre-trip alarm function is available for S-characteristic. This
function can be used to adjust feeding to loads according to
their priority.
The pre-trip alarm is automatically reset when the load current
drops to the predetermined value.
Note that this function needs the control power.
t
Ground fault trip function GF
The peak value sensing is used (the residual current of each
phase is detected).
The GF pickup current can be set between 10% and 100% of
the CT rated primary current [
I
CT
]. Not available if CT primary
current [
I
CT
] is 200A or less.
<Ramp characteristic is added>
The ramp and definite time characteristics are switch select-
able. The GF trip function comes into operation with the defi-
nite time characteristic when the load current reaches 100%
or more of the CT rated primary current [
I
CT
].
The GF trip function is factory set to the definite time charac-
teristic.
When using a 3-pole ACB in a 3-phase, 4-wire system, be
sure to use an optional CT for neutral line (see P. 39).
Note 1: The GF trip function comes usually with operation
indications. If you need nothing but ground fault
indication without a ground fault tripping operation,
specify at the time of ordering.
Note 2: Restricted and unrestricted ground fault protection
REF
is available as option. This enables protection against
ground fault on the line side of the ACB.
y
Earth leakage trip function ELT
(For AGR-31B only.)
In conjunction with an external Zero phase Current Transformer
(ZCT), the ELT function provides protection against earth leak-
age.
The ELT pickup current can be set at 0.2, 0.3, 0.5 and 1A
(Medium sensitivity) or 3 and 5A (Low sensitivity).
This function needs the control power.
Note 1:
For details on specifications of the external ZCT,
contact Terasaki.
Note 2:
The ELT function comes usually with operation
indications. If you need nothing but earth leakage
indications without ear th leakage tripping
operation, specify at the time of ordering.
Note 3:
The ELT function is available up to 2500A rated
current [
I
n
]
u
Reverse power trip function RPT
(For AGR-22B and AGR-31B only.)
The RPT function protects 3-phase generators running in par-
allel against reverse power. The RPT pickup current can be
set in seven levels: 4% thru 10% of the generator rated power.
If the rated main circuit voltage exceeds 250 VAC, a step-down
power transformer is needed. When ordering the ACB, state
the step-down ratio of the transformer you will use.
i
N-phase protection function NP
This NP function is available on 4-pole ACBs and prevents the
neutral conductor from suffering damage or burnout due to
overcurrent.
The NP trip pickup current can be set between 40% and 100%
of the OCR rated primary current for L and R-characteristics or
of the generator rated current for S-characteristic.
It is factory set to a value specified at the time of ordering.
Note 1: The NP trip function comes usually with operation
indications. The NP trip pickup current setting is shared
by the LT trip function.
Note 2: The HOT start mode is available for AGR-21B and
AGR-31B. The operating time for the NP trip function
is linked to that for the LT trip function.
Soon to be available
o
Contact temperature monitoring function OH
(For AGR-22B and AGR-31B only.)
The HEAT function prevents the ACB from suffering damage
due to overheat.
It monitors the temperature of the ACB main contacts, and
gives an alarm on the LCD and an output signal via the alarm
contact (1a-contact) when the temperature exceeds 155
°
C.
The alarm can be manually reset when the temperature drops
to a normal temperature.
If you want to set the threshold temperature to a lower value,
contact Terasaki.
This function needs the control power.
Note 1: "Alarm" or "Trip" can be selected.
!0
Phase rotation protection function NS
(For AGR-21B and AGR-31B only)
This function detects the negative-phase current occurring due
to reverse phase or phase loss and prevents burnout of a mo-
tor or damage to equipment. The protection setpoint ranges
from 20% to 100% of the main circuit rated current [
I
n
].
!1
Undervoltage alarm function UV
(For AGR-22B and AGR-31B only.)
This function monitors the main circuit voltage, and gives an
alarm on the LCD and an output signal via an alarm contact
when the voltage drops below the setting voltage.
The alarm is activated when the main circuit voltage drops
below the setting voltage (selectable from 40%, 60% or 80%
of the rated main circuit voltage [Vn]), and is deactivated when
the main circuit voltage rises to the recovery setting voltage
(selectable from 80%, 85%, 90% or 95% of the rated main
circuit voltage [Vn]).
If the rated main circuit voltage exceeds 250 VAC, a step-down
power transformer is needed. When ordering the ACB, state
the step-down ratio of the transformer you will use.
Note 1: The undervoltage alarm function is disabled unless
the main circuit voltage has once risen to the recovery
setting voltage or higher.
Note 2: If the undervoltage alarm function is used in conjunc-
tion with the undervoltage trip device (see page 24),
an alarm may occur after the ACB trips open depend-
ing on the alarm setting voltage.
!2
Zone interlock Z
(For AGR-22B and AGR-31B only)
The zone-selective interlock capability permits tripping of the
ACB upstream of and nearest to a fault point in the shortest
operating time, irrespective of the short time delay trip time
setting, and minimizes thermal and mechanical damage to the
power distribution line.
Field test facility
Type AGR-21B/22B/31B OCRs are equipped with a field test function to verify the long time delay, short time delay, instantaneous
and ground fault trip features without the need for tripping of the ACB.
To check type AGR-11B, use the type ANU-1 OCR checker (optional).
