Cooper Lighting S260-75-1 - Manual (Page 17)

Timer Settings
The two digital timers are identical. One timer controls the
time required to transfer from the preferred source to the
alternate source, the other timer controls the time to trans-
fer from the alternate source to the preferred source.
The two digital timers feature the following informational
indicators and adjustment controls:
Digital Time Display
LED displays the time count. The timer counts up until it
reaches the time delay setting of the thumbwheel switch.
Time Range Selector
The time range selector switch can be set to six different
positions with a flat screwdriver. Each position indicates a
time range. See chart below. The time range selector is
preset to the time range of 0.1 to 99.9 seconds.
Thumbwheel Time Setting
Set the desired time delay setting by rotating the thumb-
wheel switch. For example, if the thumbwheel time set-
ting is 345 the timer will time out in 34.5 seconds based
off the time range selector setting of 0.1 to 99.9 seconds.
Note: The thumb-wheel time setting, which does not turn
infinitely, should not be turned beyond the limit.
Out Indicator
The out indicator briefly lights to signal completion of a
timing interval and confirm that the timer has operated.
Normal Operation
The control will react to ongoing line voltage conditions
and operate automatically as programmed. If equipped
with the fault block accessory, transfer to the alternate
source may be prevented when loss of voltage is due to
a load-side fault. See Fault Block Operating
Instructions section for procedure to restore service.
THEORY OF OPERATION
—BASIC S CONTROL
Refer to Figures 16 and 17 for the following sections:
Voltage Sensing
The S control will transfer the load to an alternate source
when one or more phases of the preferred source is lost,
provided normal voltage is present on all three phases of
the alternate source. To perform this function, the control
requires three-phase, low-voltage (120 Vac) input from
both the preferred and alternate sources of power. Input
from Source I is connected to terminals A, B, C and G1
of TB2, and input from Source II is connected to termi-
nals X, Y, Z and G2.
Each of the three input phase leads for both Source I and
Source II is shunted to ground by a capacitor–varistor
combination to provide surge protection to the control.
On the preferred source side of the voltage sensing cir-
cuitry, the input lines then pass through 10 Amp fuses to
the voltage sensing relays: R2 (Phase A), R9 (Phase B)
and R10 (Phase C). R9 and R10 are connected directly
to the input while N.O. contacts of R9 and R10 are in
series with the R2 coil. Thus, R2 can be energized only if
all three incoming phase voltages are above a predeter-
mined value (approximately 97 volts). A similar arrange-
ment is used for the alternate source sensing relays. R6
can be energized only if R7 and R8 are energized. The
transfer bus across the top of the schematic diagram),
which provides the operating power for the control is nor-
mally energized from Phase Y. If R7 drops out, due to
loss of Phase Y, R11 will be energized from Phase B
(through N.C. contact of R7) to re-energize the transfer
bus. The contacts of R7 and R11 are so connected that
the transfer bus can never be simultaneously energized
from both B and Y phases.
S260-75-1
17
!
SAFETY
FOR LIFE
IMPORTANT: Put control in manual mode prior to
changing timer setting. There is no fault current pro-
tection when in manual mode. Failure to comply can
cause unintended operation.
S S
9 9 9
9 9 5 4 3 3.45 3.45
OUT
Thumb-Wheel
Time Setting
Decimal Point
Indicator
Time Range
Selector
OUT Indicator
Digital Time
Display
Figure 15.
Digital Timer and Time Ranges.
S
0.01
to
9.99
sec
9.99 99.9 999 99.9 999 99.9
Indication
Time
Range
S S M M H
0.1
to
99.9
sec
1
to
999
sec
0.1
to
99.9
hours
1
to
999
min
0.1
to
99.9
min
IMPORTANT: Thumb-wheel time setting must be
securely turned. Incomplete setting may cause timer
malfunction and control misoperation.