Specifications are subject to change without notice. No liability accepted for errors or omissions.
3
The
No-Break™ DC
power supply is designed to provide DC power and float charge lead acid batteries for
critical back up applications. The SR250
i
A 485 is a variant of our standard SR250CA model. In addition
to all the normal features of the
No-Break™ DC
range, the SR250
i
A 485 has a serial communication inter-
face to enable user monitoring of the power supply and user control of the battery condition test function.
No-Break
™ SYSTEM BLOCK DIAGRAM
LOAD +
I
LOAD
AC MAINS
STANDBY
LED &
BUTTON
POWER
OK LED
BATTERY
SYSTEM
OK LED
MAINS FAIL /
POWER SUPPLY
FAIL ALARM
BATTERY
SYSTEM
FAIL ALARM
LED
ON
LED
ON
LED
OFF
ALARM
OFF
ALARM
OFF
LOAD -
B
BATTERY -
NORMAL OPERATION
LOAD CURRENT < PSU MAX CURRENT
ELECTRONIC
CIRCUIT
BREAKER
POWER CONVERSION
BATTERY
MANAGEMENT
& ALARM
CIRCUIT
BATTERY
CURRENT
SENSE
OUTPUT VOLTAGE, CURRENT
LIMIT & BATTERY CHARGE
CURRENT CONTROL
I
CHARGE
BATTERY TEMP.
SENSOR
REVERSE
POLARITY
FUSE
RS485
comms. port
System Current Limit
(AC mains on)
System Current Limit
(during AC fail)
Total current
PSU + Battery
PSU current
Component
8
6x
2.5x
1x
L
o
a
d
A
m
p
s
2mS
300mS
Time
6x overload
for 300mS max.
Battery is discharging whenever load cur-
rent exceeds 1x (system current limit).
Short circuit condition
can only exist for 2mS
8
6x
1.5x
L
o
a
d
A
m
p
s
2mS
300mS
Time
6x overload
for 300mS max.
Short circuit condition
can only exist for 2mS
Indefinite
Until LVD
OPERATION OF ELECTRONIC CIRCUIT BREAKER (ECB) UNDER OVERLOAD CONDITIONS
ECB operates after 2mS under short circuit condition and after 300mS of sustained overload. At all times the ECB allows 50-60% system overload.
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