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The Type NAA relays covered by these instruc
tions are auxiliary relays for use in the various
line transferr ed trip schemes as describe d below.
The NAA27H relay is designed for use in direct
and
permissi ve
underrea ching
transferr ed trip
schemes via
Type 10 tones,
It includes three
telephon e type relay units designat ed as TX, GX,
and RI, and a target seal-in unit.
The GX and TX
units are auxiliari es to the guard and trip frequenc y
receiver units which are normally included in the
Type 10 tone receiver . The GX is normally held in
its picked up position by a contact of the guard
frequenc y receiver unit. Its function is to block the
transferr ed trip circuit and to sound an alarm upon
loss of the guard channel. The TX Unit picks up on
receipt of a transferr ed trip signal to provide an
alarm during test.
The RI unit is energize d by all
high-spe ed trip circuits,
includin g the received
transferr ed trip signal, and initiates high speed
reclosin g.
The NAA27J relay is intended for use on per
missive cverreac hing transferr ed trip schemes . It
is used in conjunc tion with the NAA27H relay when a
Type 10 pilot is involved or with the NAA27L relay
when the channel is Type 50 carrier.
It includes
three telephon e type relay units designat ed as TTY,
TTZ, and BX.
The BX unit which has a time delay
pick up of 6 cycles, (60 cycle basis) is operated by a
"b" switch on the associat ed circuit breaker to send
a continuo us transferr ed trip signal when the breaker
is open.
The TTY unit is intended as a general
purpose unit for use in the permissi ve overreac hing
scheme.
It has a normal drop out time of approxi
inately 1 cycle, but can, 11 desired, be used with an
external capacito r to obtain longer drop out times.
The TTZ unit provides the small coordina ting time
necessar y in the transferr ed trip circuit on per
missive overreac hing schemes .
The NAA27K relay is intended for use on direct
and permissi ve underrea ching or permissi ve over-
reaching schemes when multi-te rminal lines are
involved .
It is required in addition to the other
necessar y transferr ed trip auxiliari es. It includes
two telephon e type relay units designat ed as GX and
TX, which are identica l with the similar units in the
NAA27H relay.
The NAA27L relay is intended for use on direct
underrea ching transferr ed trip applicat ions where
Type 50 carrier is used as the pilot.
It includes
four telephon e type relays units, designat ed as TX,
GX, RI, and TTY, and a target seal-in unit. The
TX, GX, and RI units are identica l with the corres
ponding units in the NAA27H relay. The TTY unit is
a high-spe ed relay used to key the type 50 carrier
channel.
It should be noted that the coils of all telephon e
type units in these relays are furnishe d with surge
limiting shunt resistors .
The operatin g characte ristics of all units are
shown in the tabulatio ns accompa nying the internal
connecti on diagram s.
The Type NAA relays covered by these instruc
tions are suitable for continuo us operatio n at the
rated DC voltage shown on the namepla te and are
availabl e for 24, 48, 125 and 250 volt applicat ions.
The resistanc e values of the telephon e type relays
and associat ed resistors are listed on the internal
connecti on diagram .
The combina tion target and seal-in unit in the
NAA27H and NAA27K relays is rated as shown in
Table I.
TABLE I
RATINGS OF TARGET AND SEAL-I N UNIT
Dual Hated
'2 0
0.2
2.0
0.6
2.0
Carry 30 Amos for (Sec)
0.05
2.2
0.5
3.5
Carry 10 Amps for (Sef)
0.45
2.0
5.0
30
Carry continuously (Amp)
0.37
2.3
1.2
2.6
Minimim Operating (Amp)
0.2
2.0
0.6
2.0
Minimum Drop-out (Amp)
0.05
0.5
0.15
0.5
DC
resistance
(Ohms)
8.3
.24
0.78
0.18
60 Hz impedance (Ohms)
50
.65
6.2
0.65
50 Hz impedance (Ohms)
42
.54
5.1
0.54
DC resistive
2.5 Amp
Interrupting rating (Amps)
('125 VDC
T:yese Instractl ons do not purport to cover all details or variation s in equipment nor
to
provide for
c-er-v posshle cc.9tngency to
be
met in connection with installat ion, operatio n or maintenance.
Should
further inlarmat ioji b desired or should particula r problems
alise
which are not covered sufficien tly for
hc purh.ers purposc , the matter should
be referred to the General Electric Company.
To tsr- extent required the products describe d herein
meet
applicab le ANSI, IEEE and
NEMA
standard s;
:,ut ns
Iaruraz2 ce
is
given
with
respect to local codes and ordinanc es because they vary greatly.
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