Omron S8T-DCBU-01 User manual

DC Backup Block for S8TS S8T-DCBU-01 L-39
Power
Supplies
DC Backup Block for S8TS
S8T-DCBU-01
DC Backup Block for S8TS
for Preventing 24 VDC Outages due to
Instantaneous Power Failures
• Supplies 24 VDC for a fixed period of time even during
AC input outages to considerably improve system reliability.
• Block Power Supply Basic Block is connected by the Bus Line
Connector.
Simple system configuration
• Alarms are notified by indication on main unit and by alarm
signal output. Block Power Supply Basic Block
DC Backup Block
Ordering Information
DC Backup Block (See Note 1.)
Note: 1. One Bus Line Connector, S8T-BUS03, is included as an accessory.
2. When specified battery, LC-@122R2@@, is in use: Max. 3.7 A
When specified battery, LC-@123R4@@, is in use: The output current can be selected by the overcurrent protection operating point
selector.
Battery Holder
Basic Block
Note: Use S8T-DCBU-01 together with the Block Power Supply Basic Block(s).
For more information on the Basic Block, refer to the S8TS data sheet (Cat.No. T022-E1).
Battery
See on Page 2 for the battery ordering infomation.
Input voltage Output voltage Output current Model number
24 to 28 VDC 24 V 3.7 A/ 8 A (See note 2.) S8T-DCBU-01
Model number
S82Y-TS01
Type Input voltage
Output voltage/Output current Model number
Screw terminal type With Bus Line Connectors 100 to 240 VAC 24 V/ 2.5 A S8TS-06024-E1
Without Bus Line Connectors S8TS-06024
Connector terminal type With Bus Line Connectors S8TS-06024F-E1
Without Bus Line Connectors S8TS-06024F

L-40 DC Backup Block for S8TS S8T-DCBU-01
■Basic Configuration
Max. No. of Connected S8TS-06024@Units and Designated Battery
Note: 1. The designated battery is made by Matsushita (Panasonic).
2. The designated battery is rated at 12 V. Use two batteries in series.
3. S8T-DCBU-01 shall be connected with S8TS-06024@when in use.
4. Consult OMRON or Panasonic sales representatives when purchasing batteries.
Area where battery is sold Japan Europe Areas other than Japan
and Europe
Overcurrent
protection
operating
point selector
Max. No. of
connected
S8TS-06024@
units
LC-
P122R2J LC- P123R4J LC- R122R2PG LC- R123R4PG LC- R122R2P LC- R123R4P
5.7 A (typ.) 2 (3 in the case of N+1
redundant operation) Yes Yes Yes Yes Yes Yes
11.7 A (typ.) 4 (5 in the case of N+1
redundant operation) —— Yes —— Yes —— Yes
S8T-BUS01
Bus Line Connector
(Order separately or including
in S8TS-06024@-E1)
Connect to
Loads
Connect to
Batteries
Connect to
AC Lines
S8TS-06024@
Block Power Supply Basic Block
(Order separately) S8T-BUS03 Bus Line Connector
S8T-DCBU-01 DC Backup Block
S82Y-TS01 Battery Holder
(Order separately)
Note: One S8T-BUS03 Connector is included with the
S8T-DCBU-01 DC Backup Block.
Note: S8T-BUS01 Connector is used
for connecting to the
S8TS-06024@Basic Block.

DC Backup Block for S8TS S8T-DCBU-01 L-41
Power
Supplies
Specifications
■Ratings/ Characteristics
Note: 1. Refer to Output Voltage Adjustment for S8TS-06024@on page 44 for details.
2. The output is specified at power output terminals.
3. Specified by performance of S8TS-06024@Basic Block.
4. Specified by S8TS-06024@connection.
5. Output voltage goes down to 21.0 V (min.) when the backup operation is activated.
6. Refer to Backup Time (Reference Value) on page 51 for details.
7. Refer to Functions on page 46 for details.
8. Set the detection current to 20 mA ×N when S8TS-06024@Basic Block N Blocks are connected.
9. Be sure to mount End Plates (PFP-M) on both ends of the Power Supply.
10. To be compliant with UL508 (Class2: per UL1310), take one of following each measure. Note that the number of
S8TS-06024@to be connected to the S8T-DCBU-01 shall be one.
•Connect S8T-DCBU-01 to S82Y-TS01 having its fuse replaced with an UL-Listed and DC rated 32 VDC min./ 3 A max. one.
•Connect an UL-Listed and DC rated 32 VDC min./ 2.5 A max. fuse at the location shown in Figure 1.
Item Model S8T-DCBU-01
Input Voltage (See note 1.) 24 to 28 VDC
Output
(See note
2.)
Normal
operation Voltage 24 VDC (See note 3.)
Load variation influence
(See note 4.) 6% max.
Backup
operation Voltage 21.0 to 27.4 VDC (See note 5.)
Min. output
current
LC- @ 122R2 @@ 0.11 A
LC- @ 123R4 @@ 0.17 A
Backup time
(referencevalue)
(See note 6.)
LC- @ 122R2 @@ 8 min/ 3.7 A (at 25°C, battery fully charged, start of battery service life)
LC- @ 123R4 @@ 4 min/ 8.0 A (at 25°C, battery fully charged, start of battery service life)
Charging Method Stable voltage/current charging method
Charge voltage (See note 7.) 27.4 V/ 26.2 V (typical)
Max. charge current 0.35 A (typical)
Overvoltage protection (See note 7.) Yes (30 V typical)
Additional
functions Protection functions Backup stop function (See note 7.) Yes (18.5 V typical)
Overcurrent protection
(See note 7.) Yes (5.7 A/ 11.7 A typical)
Battery misconnection
protection (See note 7.) Ye s
Input
function Backup ON/OFF input (See note 7.) Ye s
Output
functions Output indicator Yes (color: green)
Battery status indicator
(See note 7.) Yes (color: red)
Battery status output
(See note 7.) Yes (relay: 24 VDC, 0.1 A)
Backup status indicator Yes (color: red)
Operation mode output Yes (relay: 24 VDC, 0.1 A)
Other Ambient operating temperature
(See note 4.)
Operating: Refer to the derating curve in Engineering Data . (with no condensation or icing)
Storage: −25 to 65°C
Ambient humidity Operating: 25% to 85%; Storage: 25% to 90%
Dielectric strength
(See note 4. and 8.) 3.0 kVAC for 1 minute (between all S8TS-06024@AC input terminals, and all
S8T-DCBU-01 terminals/ all S8TS-06024@output terminals; detection current: 20 mA)
2.0 kVAC for 1 minute (between all S8TS-06024@AC input terminals and GR termi-
nals; detection current: 20 mA)
1.0 kVAC for 1 minute (between all S8T-DCBU-01 terminals/ all S8TS-06024@output
terminals, and between GR terminals; detection current: 20 mA)
Insulation resistance (See note 4.) 100 MΩmin. (between all S8T-DCBU-01 terminals and all S8TS-06024@outputs,
and between all S8TS-06024@AC inputs and GR terminals) at 500 VDC
Vibration resistance (See note 4. and 9.) 10 to 55 Hz, 0.375-mm single amplitude for 2 h each in X, Y, and Z directions
Shock resistance (See note 4. and 9.) 150 m/s2, 3 times each in ±X, ±Y, and ±Z directions
Electromagnetic interference (See note 4.) Conforms to FCC Class A, EN50081-2/1993
EMS (See note 4.) Conforms to EN61000-6-2/1999
Approved standards
UL: UL508 (Listing, Class 2: Per UL1310) (See note 10.), UL60950, UL1604 (Class I /Division 2)
cUL: CSA C22.2 No.14, No.60950, No.213 (Class I /Division 2)
EN/VDE: EN50178 (=VDE0160), EN60950 (=VDE0806)
Size 120 ×120 ×43 mm
Weight Approx. 350 g
S8T-
DCBU-
01
S8TS-
06024
LN
+V
-V +V
-V
(Figure 1)

L-42 DC Backup Block for S8TS S8T-DCBU-01
Connections
■Block Diagram
Operation
■How to Use the Unit
Battery Connection
For battery connection, it is recommended that a Battery Holder
(S82Y-TS01) be used. If the S82Y-TS01 is not used, insert a switch
and a fuse between the battery and the S8T-DCBU-01. For selection
and layout of the switch and fuse, refer to Battery Holder S82Y-TS01
on page 44.
Battery Overdischarge
The battery discharges in the following three conditions (1) to (3).
When the battery has overdischarged, the battery service life may be
shortened abnormally or backup operation may be disabled due to
inability to recharge. To protect the battery against overdischarge,
take the appropriate action as described below.
(1) Discharge due to load of backup operation (See Note 1.)
Use the backup stop function (refer to page 46). Backup opera-
tion is automatically stopped when the battery connecting ter-
minal voltage drops down to 18.5 V, which prevents a rapid
discharge of the battery.
Leaving the unit in this condition for a long time, even after the
backup operation has stopped, may cause the discharge to be
hastened due to standby current of the product, thus causing
overdischarge. In that case, refer to the item (2).
(2) Discharge due to standby current of the S8T-DCBU-01
(See Note 1.)
Battery discharge is hastened by standby current consumption
that occurs due to circuit structure of S8T-DCBU-01 even if the
AC power is turned OFF and the load is not applied. In case of
Table 1, disconnect the batteries in order to protect the battery
against overdischarge. There are two ways to disconnect the
batteries as follows:
1) Turn the Battery Holder switch OFF. (See Notes 2 and 4.)
Connect the external circuit to prevent failure to turn the
switch off. (See Note 8.)
2) Open backup ON/OFF input terminals by external signal,
and disconnect the batteries by external relay. (See Figure 2
and Notes 2, 4 and 8.)
Table 1. Possibility of Overdischarge due to Standby
Current Consumption
Note: 1. The battery discharges continuously due to standby current
of the S8T-DCBU-01 even when the backup stop function is
used or when backup operation is stopped by opening the
backup ON/OFF input.
Charging
circuit
Input
voltage
detection
Detection resistorDischarge circuit
Battery misconnection
protection circuit
Bypass D
Fuse
2.0 A
Discharge
control
circuit
+
−
Battery
Backup
ON/OFF
input
Connected
to Bus Line
Connector
Connected
to Bus Line
Connector
DC (+)
DC (−)
Overcurrent
detection
+V
−V
DC OUTPUT
Operation
mode
output
X
Battery
status
output
X
Overdis-
charge
detection
Battery
voltage
detection
S8T-DCBU-01
When the battery is not disconnected:
Frequent backup
operation or
insufficient may
charge abnormally
shorten the battery
service life.
The battery
overdischarges and
cannot be recharged,
resulting in failure in
backup operation.
(See Note 3.)
Turn the AC power after
assembly OFF. (See Note 7) Ye s
Turn the AC power OFF during
maintenance or inspection.
Ye s
When the
AC power
is
frequently
turned ON
and OFF:
Turn the AC power OFF
(1 hour/day)
Ye s
Turn the AC power OFF
(16 hours/day)
Ye s
Turn the AC power OFF
for 2 days.
Ye s Ye s
Turn the AC power OFF
for about 1 week.
Ye s
Storage and transportation Ye s
Power outage for hours Ye s

DC Backup Block for S8TS S8T-DCBU-01 L-43
Power
Supplies
2. Turn the Battery Holder switch OFF or the SW shown in Fig-
ure 2. Unnecessary backup operation shortens the battery
service life for the following two reasons. When turning the
AC power OFF, be sure to turn the Battery Holder switch ON
or the SW shown in Figure 2.
•Full charge requires 24 to 28 hours. Activating backup
operation before charging fully shortens the battery ser-
vice life due to insufficient charge.
•Every time charging and discharging is repeated, the bat-
tery service life is shortened.
3. When battery connector terminal voltage drops to 15.5 V
(typical) or below, S8T-DCBU-01 stops charging due to the
erroneous battery connection protection function. When the
battery nears end of life (when the battery capacity be-
comes less than half of the original capacity), if only AC
power is turned OFF and the unit is left in this condition for
2 days (under the temperature of 25°C), backup operation
may be disabled due to inability to recharge. (Refer to Pro-
tection Against Erroneous Battery Connection on page 47.)
4. Do not use batteries in an area where corrosive gases (sili-
con gas, sulfide gas, organic gas, chlorine gas) may enter.
If the relay (“X” shown in Figure 1 and 2) or switch (Battery
Holder, SW shown in Figure 2) is exposed to corrosive gas-
es for an extended period, the contact surface corrodes,
causing unstable or loose connection, thus disabling re-
charge or backup operation.
5. The following table shows the ambient temperature and hu-
midity when using LY1-D (24 VDC). LY1-D (24 VDC) has a
built-in diode in order to absorb counter-voltage generated
by the operation coil. As this causes polarity in the opera-
tion coil, be careful when wiring. Refer to the individual cat-
alogs for details.
6. On the SW shown in Figure 2, voltage and current increase
to 15 V when opened and 2 mA when short-circuited. Be
careful when selecting the switch.
7. The standby current becomes live and discharging is has-
tened even when AC power is not wired, but the battery is
left wired.
8. Should the operator forget to turn off the Battery Holder
switch in Figure 1 or the SW in Figure 2, the backup opera-
tion continues until the battery connecting terminal voltage
drops down to 18.5 V (typical), then the battery is discon-
nected by the relay (X). If the battery is left in this condition
for a long time exceeding the period of time shown in the ta-
bles below, the overdischarge is hastened due to self-dis-
charge, thus disabling backup operation due to inability to
recharge.
Figure 1. Overcharge protection circuit when operator
forgets to turn Battery Holder switch OFF
Figure 2. Overcharge protection circuit using external
signal (Backup ON/OFF input)
(3) Self-discharge of the battery
The battery self-discharges even when it is disconnected from
the S8T-DCBU-01. When transporting or storing the unit for long
hours, charge the battery at the intervals specified below to pre-
vent overdischarge.
Ambient temperature
Ambient humidity
LY1 -D
(24 VDC)
Output current 4 A or under: − 25 to +55°C
Output current 4 A or over:
− 25 to +40°C
5 to 85%
Battery Ambient
tempe-
rature
Load
current Length of months that disables recharge
Battery
service life
early stage
Battery
service life
ending stage
LC-@122
R2@@ 20 °C 0.11 A 1.0 month 0.5 months
2.2 A 2.0 months 1.0 month
40 °C 0.11 A 0.5 months 0.25 months
2.2 A 1.0 month 0.5 months
LC-@123
R4@@ 20 °C 0.17 A 1.0 month 0.5 months
4.8 A 3.0 months 1.5 months
40 °C 0.17 A 0.5 months 0.25 months
4.8 A 3.0 months 1.5 months
Ambient temperature Charging intervals
Under 20 °C 9 months
20 to 30 °C 6 months
30 to 40 °C 3 months
X
X
S82Y-TS01 (Battery Holder)
S8T-DCBU-01
LOAD
LN +−
+V−V
−V
+V
X
Specified relay (X): LY1-D (24 VDC)
<OMRON> (See Note 5)
1
3
5
78
6
4
2
S8TS
-06024@
LY1-D (24 VDC)
When forgetting to turn Battery Holder switch OFF:
1. Start backup operation after turning OFF AC power.
2. When the battery connecting terminal voltage drops down to
18.5 V (typical), the backup operation stops, opening the relay point and
disconnecting the battery from the body.
(Backup ON/OFF Input)
S82Y-TS01 (Battery Holder)
Specified relay (X): LY1-D (24 VDC)
<OMRON> (See Note 5)
S8T-DCBU-01
LN
LOAD
+V−V
X
−V
+V
+−
X
SW (See note 6.)
S8TS
-06024@
1. Open the backup ON/OFF input terminals by external signal (switch)
(Backup becomes impossible.)
2. When AC power is turned OFF, 24 VDC drops, opening the relay point
and disconnecting the battery from the DC Backup Block body.

L-44 DC Backup Block for S8TS S8T-DCBU-01
Backup Function
(Backup status indication, Operation mode output)
S8T-DCBU-01 detects output voltage drop of S8TS-06024@to
switch to backup operation.
Backup operation continues for about 7 seconds even after the out-
put voltage of S8TS-06024@is restored.
* If this state occurs, a probable cause is an S8TS-06024@overload
or it is out of order. Immediately eliminate the cause of the trouble.
Note: 1. If switching between backup operation and Normal opera-
tion is repeated, the output voltage changes accordingly.
2. The contact capacity of the relay is 24 VDC 0.1A.
3. Do not use the battery upon a steep load fluctuation or at a
peak load exceeding the rated current. The output voltage
of S8TS-06024@may drop to switch to backup operation,
and shorten the battery service life.
4. The maximum inrush current specified below (on assump-
tion with a 56000 µF capacitive load) flows when backup op-
eration starts.
Charging Circuit
Charging Time (Reference Values)
Note: The battery takes the time specified above to be charged. If
power failure occurs at a time shorter than the necessary
charging time (power failure right after the setup, or repeated
failure in a short period of hours), backup operation may not
continue for the necessary time.
Output Voltage Adjustment for
S8TS-06024@
The DC Backup Block detects output voltage drop of connected
S8TS-06024@to switch to backup operation.
Do not set the output voltage of S8TS-06024@to lower than the fac-
tory shipment setting because, even though the output voltage of
S8TS-06024@is adjustable with Output voltage adjustor. Otherwise,
it may operate in the backup operation mode.
Wiring Length Between S8T-DCBU-01
and Battery
Connect S8T-DCBU-01 and the battery using a cable having a wire
diameter specified in Recommended Wire Diameter (page 55) within
a wiring length of 1.5 m.
Because the battery voltage is monitored at the battery connecting
terminal, a large wiring impedance increases the voltage drop from
wiring, reducing the backup time.
Battery Holder S82Y-TS01
We recommend using the S82Y-TS01 Battery Holder for connecting
and installing the battery. Take the following points into consideration
when using the S82Y-TS01:
(1) Contact between leaking battery fluid and metal parts having an
electric potential may cause smoke or fire. To prevent this, the
Battery Holder uses a resin battery tray.
Set up the Battery Holder in the direction shown below.
(2) The inrush current shown below flows when backup operation is
switched to. The peak value and time of this inrush current vary
according to the capacity of the input capacitor of the connected
equipment, battery charge status, battery wiring length, and
ambient temperature. The switch and fuse of the S82Y-TS01 are
selected taking this inrush current into consideration. When
replacing the fuse, use only the specified fuse. (Littelfuse,
257015 (15 A))
(3) In the event that the battery generates inflammable gases, place
the switch and fuse away from the convection path of the inflam-
mable gas to prevent the switch or fuse from causing ignition and
explosion.
(4) Keeping the S8T-DCBU-01 connected to the battery with AC
power OFF may cause the battery to overdischarge due to
standby current of the S8T-DCBU-01, which may considerably
shorten the service life of the battery and may disable recharg-
ing. To prevent this, turn the switch OFF. (Refer to Battery Over-
discharge on page 42.)
Backup
status LED
(BACKUP: Red)
Relay
(OPN MODE )
Power failure Continuous
backup
operation
Lit Backup
(1)-(2): ON
Failure
of one
unit of
S8TS-
06024@
During
operation of
one unit of
S8TS-06024
@
During
operation of
multiple units
of S8TS-
06024
@ *
Repetition of
switching be-
tween Normal
operation and
Backup oper-
ation at an in-
terval of about
7 seconds
Blink at an
interval of
about 7
seconds
Repetition of
switching
between
Normal
((3)-(2): ON)
and
Backup
((1)-(2): ON)
Upon activation of
overcurrent protection
function of S8TS-
06024
@ *
Battery used 100% charged 80% charged
LC-@122R2@@ 24 to 48 hours 5 hours
LC-@123R4@@ 8 hours
COM
Normal
Backup
Relay (OPN MODE)
(1)-(2): ON
Operation mode
output relay
Indicator
1
2
3
LED lit
(DC ON: Green)
LED lit
(BACKUP: Red)
45
0Time
Battery charge status: Fully charged
Ambient temperature: 40˚C
Input capacitor of connected equipment: 56,000 µF
Load power: 192 W
25 ms
Inrush current (A)
45
0Time
Battery charge status: Fully charged
Ambient temperature: 40˚C
Input capacitor of connected equipment: 56,000 µF
Load power: 192 W
25 ms
Inrush current (A)

DC Backup Block for S8TS S8T-DCBU-01 L-45
Power
Supplies
Mounting and Removing the Bus Line
Connector
Pay attention to the following points to maintain electrical characteris-
tics.
•Do not insert/remove the Connectors more than 20 times.
•Do not touch the Connector terminals.
•To remove the Connectors, insert a flat-bladed screwdriver alter-
nately at both ends.
S8T-BUS03
Use S8T-BUS03, which only DC lines are connected with. (AC line
not connected).
S8T-BUS03 is equipped with a selector for the prevention of errone-
ous connection of a different output voltage specification of the
power supply unit. Slide the selector in the 24 V position.
Mounting
Mounting Direction
Use standard mounting only. Using any other mounting method will
prevent proper heat dissipation and may result in deterioration or
damage of internal elements.
Operation Check
After connecting S8TS-06024@and S8T-DCBU-01, it is recom-
mended to check the DC Backup Block if it is correctly operating in
the following procedure.
1. Turn ON the Battery Holder.
2. Turn ON the AC power to the S8TS-06024@.
3. Wait for 10 sec. or more then check if the DC Backup Block is in
Status 1.
4. Turn OFF the AC power of the S8TS-06024@.
5. Confirm that Backup operation is correctly performed in Status 2.
6. Turn ON the AC power of the S8TS-06024@.
Note: 1. Perform operation checks after arranging a state where no
fault occurs even if the connected devices are turned OFF
in the midway.
2. The operation mode may not changed to Backup, if AC pow-
er is turned OFF within 10 sec. at Step 3.
3. When turning the AC power OFF or storing or transporting
the unit after operation checks, follow the instructions de-
scribed in Battery Overdischarge on page 42.
Standard mounting Yes
Back down mounting No
Other mounting No
Selector
−V+V −V+V
−
LNGR
S8T-BUS03S8TS-06024@
S8T-DCBU-01
+
Standard mounting Back down mounting
COM
OK
LOW
Relay (BAT LOW)
(6)-(5): ON
Battery status
output relay
4
5
6
LED lit
(DC ON: Green)
Relay (OPN MODE)
(3)-(2): ON
Operation mode
output relay
Indicator
1
2
3
COM
Normal
Backup
4
5
6
1
2
3
COM
OK
LOW
Relay (BAT LOW)
(6)-(5): ON
Battery status
output relay
LED lit
(DC ON: Green)
LED lit
(BACKUP: Red)
Relay (OPN MODE)
(1)-(2): ON
Operation mode
output relay
Indicator
COM
Normal
Backup

L-46 DC Backup Block for S8TS S8T-DCBU-01
■Functions
Charging Voltage Selector
Select either 27.4 V or 26.2 V at the charging
voltage selector to select the charging volt-
age.
Because the battery manufacturer recom-
mends 27.4 V as charging voltage, it is rec-
ommended to charge at 27.4 V.
In this case, 27.4 VDC, which is the charging
voltage of the batteries, may output depend-
ing on the state of connected load when the
operation changes to Backup.
Note: If the battery is charged at 26.2 V, the battery capacity decreas-
es each time the battery is charged, and the backup time grad-
ually decreases.
(Reference value)
Overvoltage Protection Circuit
If the charge voltage is about 30 V or above, the charge voltage is cut
off to prevent the battery from being overcharged.
How to Reset Overvoltage Protection
Reset Overvoltage protection with following steps after arranging a
state where no fault occurs even if the connected devices are turned
off in the midway.
1. Turn OFF the Battery Holder switch.
2. Turn OFF the AC power of the S8TS-06024@.
3. Leave the power supply OFF for 1 minute or more.
4. Turn ON the Battery Holder switch.
5. Turn ON the AC power of the S8TS-06024@again.
Note: 1. Remove the cause before turning on the AC power again.
2. As an AC input OFF status is the same as a power failure,
the S8T-DCBU-01 will perform backup operation. Some-
times charging cannot be performed for the required backup
time as the battery is not sufficiently charged. For this rea-
son, first make sure that backup operation is not needed be-
fore turning the Battery Holder switch and then the AC input
OFF.
3. The off time necessary for restoration assumes connection
of five units of S8TS-06024@, without a load, and fully
charged batteries.
Overcurrent Protection Operating Point
Selector
5.7 A (typ.) or 11.7 A (typ.) can be selected
with the selector as an overcurrent protec-
tion operating point during backup operation.
Select 5.7 A (typ.) for one or two units of
S8TS-06024@(or three units during N+1
redundancy operation), or select 11.7 A
(typ.) for three or four units (or five units dur-
ing N+1 redundancy operation). The ship-
ment setting is 5.7 A (typ.).
Overcurrent Protection Function
During Normal Operation
An overcurrent is notified in the following way.
•LED (BAT LOW: Red) lights up.
•Relay (BAT LOW) is in the LOW mode ((4)-(5): ON).
If power failure occurs in this state, an overcurrent protection function
is activated to fail to backup.
During Backup Operation
The overcurrent protection operating point can be selected from
either 5.7 A (typ.) or 11.7 A (typ.) using the selector. The output is
cut off when overcurrent protection is activated.
Note: Continuation of operation in the overcurrent status may cause
deterioration or breakage of internal elements.
Backup Stop Function
When the battery connecting terminal voltage drops down to 18.5 V,
backup operation is automatically stopped to protect the battery
against overdischarge due to load current.
Note: 1. Battery discharge is continued by standby current con-
sumption of the S8T-DCBU-01 even when backup operation
is stopped. Do not leave the unit in this condition for a long
time. (Refer to Battery Overdischarge on page 42.)
2. Remaining battery capacity is zero when the battery voltage
is 18.5 V (typical).
Backup ON/OFF Input Function
If the backup ON/OFF input terminals are short-circuited, backup is
enabled, while if the terminals are open, backup is disabled. The ter-
minal is non-voltage input type and the short and open circuits are
specified below.
With the shipment setting, a short bar is installed to short-circuit
across the backup ON/OFF input terminals.
When the backup ON/OFF input terminals are open, the following
signs inform that backup is disabled.
•LED (BAT LOT: Red) is lit.
•Relay (BAT LOW) is in the LOW mode ((4)-(5): ON).
Note: Battery discharge is continued by standby current consumption
of the S8T-DCBU-01 even when backup operation is stopped.
Do not leave the unit in this condition for a long time. (Refer to
Battery Overdischarge on page 42.)
Capacity reduction in each charge-and-discharge cycle
At 25ºC Reduction by 10%
At 0ºC Reduction by 20%
Terminal
block cover
Overcurrent protection
operating point selector
Section A
Charging voltage selector
Charging voltage selector
Enlarged View of
Section A
Short Impedance with 1 kΩor below
Flowing current at 0 Ω: About 2 mA
Residual voltage: 1 V or below
Open Impedance: 400 kΩor more
Overcurrent protection
operating point selector
Enlarged View of
Section A

DC Backup Block for S8TS S8T-DCBU-01 L-47
Power
Supplies
Protection Against Erroneous Battery
Connection
When the DC Backup Block is turned on, the charging circuit is sepa-
rated if battery connection terminal voltage become below about
15.5 V. This function protects the battery and the main body upon
erroneous connection of the batteries (with reverse polarity or with
only one 12 V battery).
Activation of the erroneous battery connection function is notified in
the following way.
•LED (BAT LOW: Red) lights up.
•Relay (BAT LOW) is in the LOW mode ((4)-(5): ON).
Note: 1. When the battery is disconnected while the AC power is ON
after the battery is connected in a normal way (Battery Hold-
er switch OFF, Battery Holder fuse blown, battery connec-
tion wires off), the indication of battery status or output will
not respond.
2. Do not replace batteries when the AC power is on. The er-
roneous battery connection protection function will not be
activated even if the unit is connected with the polarity re-
versed, but the S8T-DCBU-01 will be damaged, and the Bat-
tery Holder fuse will be blown.
Battery Status Indication and
Battery Status Output
A battery charging/discharging fault (1. through 4. described below)
is notified in the following way.
If power failure occurs in this state, backup operation does not start
or the backup time becomes shorter. Remove the cause of the fault
immediately.
1. About 22.5 V or lower battery connecting terminal voltage (BAT
LOW will be released when the voltage goes up to 24.5 V or over).
2. Activation of erroneous battery connection protection function.
3. Open battery ON/OFF input terminals.
4. Overcurrent status during Normal operation.
Note: 1. Even if BAT LOW is released, it doesn’t mean that the bat-
tery charging is finished.
2. Relay contact capacity is 24 VDC and 0.1A.
■Battery Replacement
The lead battery deteriorates.
Replace the battery while referring to the following replacement
period as a reference.
Note: 1. Battery deterioration accelerates when its service life limit
draws near.
2. The battery replacement timing assumes the battery has
reached half its original capacity.
3. The life varies according to the storage and operating envi-
ronment, output wattage, and the frequency of backup op-
eration.
4. Fire may be caused in worst case, if batteries are continu-
ously used beyond its replace timing. Replace batteries pe-
riodically to avoid the worst case.
5. Do not replace batteries when the AC power is on. The er-
roneous battery connection protection function will not be
activated even if the unit is connected with the polarity re-
versed, but the S8T-DCBU-01 will be damaged, and the Bat-
tery Holder fuse will be blown.
1. Replacement Guideline
Replace the battery using the following table as a guideline:
Note: The conditions in the table above is estimated as: charged at
27.4 V, discharged with 8 A (for LC-@123R4@@), 3.7 A (LC-@
122R2@@), backup operation once a month bases.
2. Measuring Backup Time
The backup time can be measured by the procedure below. When
the battery is new, first measure the initial backup time value.
Replace the battery if backup operation is not performed for the
required backup time during periodic maintenance or the backup
time has fallen below the half or less of initial value.
Note: 1. Make sure that at least 48 hours have elapsed since the pre-
vious backup operation, and that the battery is correctly
connected, and then measure the backup time.
2. Measure the backup time after making sure that no prob-
lems will occur as a result of stopping power supply.
(1) Turn the AC power line OFF, and backup the S8T-DCBU-01.
(2) Measure the time that the battery status output relay turns to
LOW ((4)-(5): ON) after the operation mode output relay is
backed up ((1)-(2): ON). (This is the backup time.)
(3) When the battery status output relay turns LOW ((4)-(5): ON),
turn the AC power line ON.
COM
OK
LOW
LED lit
(BAT LOW: Red)
Relay (BAT LOW)
(4)-(5): ON
Battery status
output relay
Indicator
4
5
6
Battery Ambient
temperature Life of battery Approximate replacement
interval
LC-R122R2@@
LC-R123R4@@ 20 °C 2 to 3 years 2 years
30 °C 1 to 1.5 years 1 year
40 °C 0.5 to 0.75 years 0.5 years
LC-P122R2@@
LC-P123R4@@ 20 °C 4 to 6 years 4 years
30 °C 2 to 3 years 2 years
40 °C 1 to 2 years 1 year
Backup time
22.5 V (typical)
AC input
Output voltage of the
S8TS-06024
Output voltage of the
S8T-DCBU-01
Backup
((1)-(2))
Operation
mode output Normal
((3)-(2))
LOW
((4)-(5))
Battery
status output OK
((6)-(5))
Battery connecting
terminal voltage

L-48 DC Backup Block for S8TS S8T-DCBU-01
Periodic Inspection of the Battery
We recommend periodically inspecting the battery as follows:
•Check the battery connecting terminal voltage. (In a 27.4 V series
connection, make sure that each battery is charged to 13.7 V.)
•Check battery wiring and connections. (Check the batteries and
S8T-DCBU-01 connections for loose screws.)
•Make sure that backup operation is performed normally in a simu-
lated power failure state.
Note: Check the backup operation after making sure that no problems
will occur as a result of stopping power supply.
Installation
DC Backup Block
Bus Line Connector
S8T-BUS03
(1) Selector
(2) Ground Terminal
(3) NC
(4) DC Output Terminal (+)
(5) DC Output Terminal (−)
Battery Holder
S82Y-TS01
(1) Battery Tray
(2) Fuse
(3) Terminal Block
(4) Switch
(5) Battery A (Order separately)
(6) Battery B (Order separately)
(7) Protection Cover
Operation mode output
(OPN MODE)
Battery status output
(BAT LOW)
Backup ON/OFF input
(ON/OFF)
2
1
3
4
5
6
7
8
9
10
11
20
22
23 24
21
14
191718 15
15
1312
16
COM
Normal
Backup
1
2
3
COM
OK
LOW
4
5
6
S
8T-D
C
BU-01
(1) Backup: Operation Mode Output Relay
(2) COM: Operation Mode Output Relay
(3) Normal: Operation Mode Output Relay
(4) LOW: Battery Status Output Relay
(5) COM: Battery Status Output Relay
(6) OK: Battery Status Output Relay
(7) ON/OFF: Backup ON/OFF Input
(8) GND: Backup ON/OFF Input
(9) Output Indicator (DC ON: Green)
(10) Backup Status Indicator (BUCKUP: Red)
(11) Battery Status Indicator (BAT LOW: Red)
(12) Battery Connecting Terminal (−)
(13) NC
(14) Battery Connecting Terminal (+)
(15) Slider
(16) Short Bar
(17) DC Output Terminal (−V)
(18) NC
(19) DC Output Terminal (+V)
(20) Rail Stopper
(21) Connecting part of Bus Line Connector
(22) Terminal Block Cover
(23) Charging Voltage Selector
(24) Overcurrent Protection Operating Point
Selector
1
2
3
4
5
42
1
5
6
3
7