Technical Specifications:

• Model Code: 915U-2-900US
• Type: Sealed Lead-Acid (SLA) Battery Backup Unit
• Number of Battery Slots: 2 slots
• Battery Type: Sealed Lead-Acid (maintenance-free, VRLA)
• Battery Capacity: 900 mAh (per battery, 12 V)
• Output Voltage: 24 VDC (nominal)
• Output Current: 900 mA (maximum continuous discharge)
• Backup Duration: Approximately 30 minutes at full load (900 mA)
• Charging Voltage: 27.6 VDC (float charge), 28.8 VDC (boost charge)
• Charging Current: 90 mA (trickle charge, continuous)
• Input Voltage: 120 VAC (US specification), 60 Hz
• Power Consumption (Charging Mode): ≤ 5 W
• Operating Temperature Range: 0°C to +55°C
• Storage Temperature Range: -20°C to +70°C
• Relative Humidity: 5% to 95% RH (non-condensing)
• Battery Life: 5 years (typical, at 25°C ambient)
• Recharge Time: ≤ 8 hours (from fully discharged)
• MTBF: ≥ 50,000 hours
• Dimensions (W × H × D): 25 mm × 90 mm × 100 mm (approx.)
• Weight: Approximately 800 g (with batteries installed)
• Mounting Method: DIN rail (35 mm) mounting inside DCS cabinet

Functional Features:

• Provides automatic switchover from AC mains to battery on power failure (transfer time: < 10 ms)
• Automatic recharge when AC mains is restored
• LED indicators: CHARGE (green), BATTERY (green), ALARM (red)
• Low battery alarm output to DCS (dry contact, NO/NC)
• Battery test button for periodic capacity verification
• Supports hot-swap battery replacement (with DCS in operation)
• Compatible with CENTUM VP CPU cards (FCU, FCIU, etc.)

Structural Features:

• DIN rail-mountable metal/plastic housing
• Battery compartment with hinged cover for easy battery access
• Terminal block for 24 VDC output and alarm contact
• Ventilation slots for heat dissipation during charging

Material Composition:

• Housing: ABS resin (UL94 V-0)
• Battery: Lead-acid, VRLA, ABS case
• Terminals: Brass, nickel-plated
• Internal wiring: Silicone-insulated wire, 105°C rated

Applicable Industries:
Oil & Gas, Petrochemical, Power Generation, Water/Wastewater, Chemical Processing — any facility using CENTUM VP DCS requiring uninterrupted operation

Installation Requirements:

• Install on 35 mm DIN rail inside CENTUM VP CPU cabinet
• Connect 120 VAC input with dedicated circuit breaker (rated 1 A)
• Connect 24 VDC output to DCS power bus terminals
• Install battery alarm contact to DCS digital input for monitoring
• Replace batteries every 5 years or when capacity drops below 80%

Precautions:

• Do not install in environments exceeding 55°C — reduces battery life
• Do not short-circuit battery terminals — risk of fire
• Do not dispose of batteries in regular trash — recycle as hazardous waste (lead-acid)
• Verify battery voltage ≥ 24 VDC before connecting to DCS
• Perform battery load test quarterly using test button
• Do not mix old and new batteries in the same unit