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Testing
On models with targets the Overload target should indicate
when
tripping
occurs,
Note:
While
timing
out
at
values slightly above pick-up
with
the
"Thermal
Memory" switch "Out,"
normal
variations in supply
voltage may cause the device
to
drop out momentarily
and
cause
the
timing to be
interrupted.
lt is
recommended that the
pickup
LED
be
monitored throughout the test. Also,
for
the
same reason, attempting
to
test Long Time timing at less than
20
percent above
the
current setting
may not be successful.
Thermal Memory Test
The
"Thermal Memory"
function accumulates the Long
Time
signal and provides a cool down function for the Long
Time
delay. Switching the thermal memory
"Out"
disables
the
inte-
grator and
allows
the
long time delay elements
to
reset when
ever
the
long time signal
drops
below pickup.
When
the
"Thermal Memory" swrtch
is
"ln" the long time delay elements
are
not reset when
the
signal
drops
below
pickup, but
are
decreased
slowly with time.
To
check the operation of the circuit, set Long
Time Current
Setting on
,5,
Long Time Delay on 3.5
and
move the "Thermal
Memory" switch
to
"1n."
Make sure the
switch
above
the
LED
timer readout on
the
PTS4 is set
to
"Static
Trip
lll
Long Time."
Apply
.55
amperes
to
one phase input and allow the
device
to
time out. Record the time. Move the "Thermal Memory" switch
to
"Out," repeat
the same
test and record
the
time.
lt
should be
the
same as the first test.
Now move
the
"Thermal Memory" switch
back
to
"1n."
Repeat
the
test,
but this
time
momentarily lower
the current every
10
seconds
to 0,2 ampere for
approximately
3
seconds
until the
long time
pickup
LED
goes out.
Be
very careful
to
not drop
below 0.15
amperes.
Again,
measure
and
record
tripping
time. This
should
be
approximately
the
same
as
for the
f
irst
two
tests.
Move
the "Thermal Memory" switch
to
the "Out" position
and
repeat this test.
ln
this case the
device should
never time
out
and
it
should be possible
to
continue
the
cycle
indef initely.
Short Time Delay Test
To
test, set lnstantaneous to
its
maximum
and
move the small
selector switch labeled
Short
Time
l2t
to
"Out,"
Move the
switch
above
the
LED
timer
readout on the
PTS4
to
"All Other Tests"
and
select
the
phase
to
be
tested,
Set
Long Time
Current
Setting on
.5 Short
Time
Pickup
on
2X, set
the
PTS4
test
set
current source for
21o
3
amperes, close the breaker and
apply
the
current.
The
breaker should
trip
within
the Iimits
of
the
Short
Time Band selected.
On
modeis
with
Targets
the Short
Circuittarget
should operate,
On
models
with
Zone lnterlocking
the time
delay
will
be
approximately
0.1
second
with the
Zone
lnterlock
switch
"1n."
The
operation
of
the
Short
Time
l2t
ramp can be checked
by
supplying 1.5
amperes
to the
device.
Repeat
the test
to
measure the time
delay.
Move the Short
Time
l2t
ramp
switch
to
the
"
ln"
position, and repeat
the test
at
the
same current.
The
delay should be
long with the
switch
"1n."
Ground
Time
Delay
Test
The Ground time delay
can
be
tested similar
to
the
Short
Time
delay
test. When the
tripping
output appears,
the
Ground
Fault
target
appears.
Zone
lnterlock
Test
On
devices with
the
Zone lnterlock option, both
the Short
Time
and
the
Ground time delay bands
are
affected
bythe
incoming
Zl
signal. With
no
incoming Zl signal
both
time delay bands
will
be
on
their
minimum. When
an incoming
Zl
signal
is present
both the
ShortTime and Ground delay elements operate
on
the
band selected
by the
front
panel controls.
On
devices containing the
Zl
function, Ihe
Zl
output circuit
provides
an
output signal anytime either
the
Short
Time
or
Ground pickup
values are
exceeded.
Both the
incoming
and
outgoing Zl circuits
are isolated by
an
optical
isolator inside
the device, so
some power
must
be
provided
to the
trip devices,
as in normal operation,
Both sets
of
signals
are
brought out
the
l5
pin
connector.
Terminal
numbering
is
from
1
through
15.
Pin
I
and
2 arelhe
device negative
power.
Pin
3
is
the
device
+12
volt
power
Pin
4
is
the
+5 volts from the
target
power
supply
Pin
5
is
the
Zl
positive
signal
input
Pin
6
is
the
Zl
negative
signal
input
Pin
7
is
the
Zl
negative
signal
output
Pin
8
is
the
Zl
positive
signal
output
The
signals from
the
15
pin
connector
are
connected together
into
a
Zone
lnterlocking System
through
a
Zone
lnterlock
Coupler
and/or
Zone
Interlock
Expander mounted
in
the
breaker
cubicle.
To
check
the
operation
of lhe
Zl
i
n
put
ci
rcuit,
set the Short
Time
and Ground time delay bands above minimum band
so that
a difference
in
timing can be detected.
Move the Short Time
l2t
switch
to
the
"out" position and Zone Interlock switch
to
the
"ln"
position. Run
the time
delay
test as
described
pre-
viously. The
measured times should correspond to the
mini-
mum time
delay,
regardless
of
setting, Now plug the
Zl
signal
tester (18-732-790-563)
into
the
15-pin
connector
on
the front
of the
trip
unit. The
LED
on the
Zl
tester indicates when
an
outgoing Zl signal
is
present, and should
Iight
whenever Short
Time
or
Ground Pickup occurs,
The
smalltoggle
switch
on
the
Zl
tester
can
be used to
activate
an
incoming Zl
signal to the
trip
unit. With
the incoming
Zl blocking
signal switched
on,
the
measured delay
should correspond
to
the time delay setting,
not the minimum delay.
lf
the short time
l2t
switch
is
"ln," the incoming Zl signal will
not
change the time delay
unless
the current used
in
the test
is
above
the
range where
the
l'?t
ramp circuits
affect the delay.
31
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