MEAN WELL DRS-240-12CAN is a 12 V DIN rail security power supply combining DC UPS backup, a battery charger and status monitoring. It provides a 0–20 A load-current range and up to 15.4 A battery charging within a shared 240 W total budget. This version has CANBus communication, with load-priority charging and two- or three-stage charging curves. Apply the input, battery and thermal limits for the installation.
Product Datasheet
Download MEAN WELL DRS-240 Datasheet (PDF)
The DRS-240 section is on PDF pages 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34. Refer to the complete mechanical drawings and notes when planning installation.
Model and Configuration
Complete model: DRS-240-12CAN; Series: DRS-240; Communication version: CAN suffix: built-in CANBus; Product functions: AC/DC supply, DC UPS, battery charger and status monitoring.
The load and charging outputs share one total power budget. Load priority automatically reduces charging current as the main-load demand increases. With a correctly selected external battery, the unit can supply the load during a mains interruption.
Designed for public-safety backup, security and alarm systems, emergency lighting, central monitoring, telecommunications and industrial automation. The catalogue states a three-year warranty.
Output Ratings and Shared Power
Nominal output voltage
12 V
Load current range
0–20 A
Maximum battery charging current
15.4 A
Rated total output power
240 W
Short-duration supply peak
275 W, within 5 s
Recommended battery capacity
20–200 Ah
Maximum ripple and noise
150 mVp-p
Voltage tolerance
±1.0%
Line / load regulation
±0.5% / ±0.5%
The combined power of all channels must not exceed 240 W in normal operation. The stated load-current maximum and charging-current maximum are not unrestricted simultaneous ratings. Load demand has priority over battery charging.
The nominal output is not a fixed battery charging voltage. With a battery connected, the output varies with the charger voltage; the default boost and float settings and selectable curves are listed below. Verify that the connected load accepts the applicable voltage range.
The recommended ampere-hour range is a selection guide. Consult the battery manufacturer about charging-current limits, chemistry and operating conditions. The external battery is selected separately.
Unless otherwise stated, specifications are measured at 230 VAC input, rated load and 25°C ambient. Voltage tolerance includes set-up tolerance plus line and load regulation. Ripple/noise uses 20 MHz bandwidth and a 12-inch twisted pair terminated with parallel 0.1 µF and 47 µF capacitors.
Input, Efficiency and Timing
AC input range
90–305 VAC
DC input range
127–431 VDC
Input frequency
47–63 Hz
Typical efficiency
90%
Typical power factor
>0.98 at 115 VAC; >0.95 at 230 VAC, full load
Typical AC input current
2.8 A at 115 VAC; 1.4 A at 230 VAC
Typical cold-start inrush
30 A at 115 VAC; 60 A at 230 VAC
Set-up / rise time
2400 ms / 1000 ms at 115 or 230 VAC, full load
Typical hold-up time
10 ms at 115 VAC; 16 ms at 230 VAC, full load
The universal input includes 277 VAC systems, subject to the published input and installation limits. Active power-factor correction is included. The block diagram marks an 80 kHz PFC stage and 65 kHz PWM stage.
Set-up time is measured at the first cold start. Repeated input ON/OFF cycling can increase this time. Apply the low-input derating curve as well as the ambient-temperature curve.
Charging Stages and DIP-Switch Curves
Default constant-current setting
15.4 A
Default boost charge voltage
14.4 V
Default float charge voltage
13.8 V
Charging-current adjustment
20–100% by front-panel VR
DIP switch 1
OFF: three stages, factory default; ON: two stages
Two-stage charging uses constant current followed by constant voltage, then stops charging when the taper-current condition is reached. Three-stage charging adds a float stage. The default taper-current point is 10% of the constant-current setting; the charging diagrams show orange during CC/CV and green for battery-full/float.
DIP switches 2 and 3 select the curves below. The same boost settings apply to two-stage charging; float voltage applies only in three-stage operation. The listed constant-current default applies to all four presets for this model. Confirm the battery manufacturer’s recommended voltages before selecting a preset.
Supported battery categories include flooded, gel and AGM lead-acid batteries and suitable lithium-ion batteries. The preset table specifically lists AGM/LiFePO4 for the ON/ON position; chemistry names alone do not establish compatibility with every battery or BMS.
Model-Specific Charging Presets
DIP 2/3 OFF/OFF — default programmable
Boost 14.4 V; float 13.8 V; CC default 15.4 A
DIP 2/3 ON/OFF — gel
Boost 14 V; float 13.6 V; CC default 15.4 A
DIP 2/3 OFF/ON — flooded
Boost 14.2 V; float 13.4 V; CC default 15.4 A
DIP 2/3 ON/ON — AGM / LiFePO4
Boost 14.6 V; float 14 V; CC default 15.4 A
Communication and Optional Programming
Charging parameters can be modified through CANBus commands for this exact model. Use the manufacturer’s current DRS communication manual for command definitions, permitted values and alarm settings.
The RJ45 communication port uses pin 6=CANH, pin 7=CANL and pin 8=GND-AUX. Pins 1–5 are NC and reserved. GND-AUX is isolated from the main +V/−V output terminals. The application diagram shows a suitable USB-CAN interface between the port and a computer.
SBP-001 is a separately sold smart programmer supported by this CANBus version. It configures the default programmable charging curve with a computer, including constant current, taper current, constant/boost voltage, float voltage, two- or three-stage operation and charging timeout settings. Leave DIP switches 2 and 3 OFF to select the programmable default curve.
The default 10% taper-current setting can be adjusted from 2% to 30% through SBP-001 with its computer software or through the CANBus interface. Use the model-specific current and voltage limits rather than the demonstration values in a software screenshot.
The illustrated DRS communication cable is labelled SBP#2. It connects the programmer’s HRS DF11-10DS 10-pin connector, or equivalent, to RJ45 on the DRS. Programmer pin 5 (CANH) goes to DRS pin 6 with a green wire; pin 6 (CANL) goes to DRS pin 7 with white/brown wire; pin 10 (GND) goes to DRS pin 8 with brown wire.
The SBP#2 drawing marks a 180 mm cable reference with CAT.5e 24 AWG PVC UTP and UL1061 28 AWG branch leads. The computer link is USB Type A to Mini USB on the programmer. Obtain the DRS-specific cable and required USB connection with the programmer order. The cable drawing’s additional PMBus branch does not make this power supply a PMBus model.
DC UPS, Battery Start and Battery-Assisted Boost
With AC input available, the supply powers the main load and charges the battery within the shared power budget. When AC fails, the UPS switches to battery power within 10 ms. Backup duration depends on battery capacity, state of charge and load; this is not a zero-time transfer guarantee.
The published AC-failure threshold is 79–89 VAC for the 120 VAC condition and 132–187 VAC for the 220 VAC condition. The relay changes state on AC failure. These alarm thresholds are separate from the normal 90–305 VAC operating range.
Battery start allows the system to restart directly from the battery without AC. The front-panel Battery Start button is provided. On CN1, pins 7 and 8 are open for normal operation and shorted for force start; use the illustrated control wiring.
With a suitable battery contributing the extra current, Power Boost Mode supports twice the rated load current for at most 4 minutes or three times for at most 4 seconds. These are battery-assisted load-output limits, separate from the supply’s 275 W / 5 s peak rating. Size the battery, output wiring and connected load for the actual transient demand.
The catalogue backup table is illustrative and assumes battery capacity at the C10 discharge rate. For example, a 20 Ah battery is shown giving 350 minutes at 3 A or 60 minutes at 10 A; actual runtime must be determined for the selected battery and installation.
Protection and Recovery
Overload threshold
105–135% of rated output power
Load-output overvoltage threshold
16.2–18.6 V
Battery cutoff voltage
10.5 V ±0.3 V
Battery-low alarm threshold
Below 11 V ±0.2 V
Short circuit uses constant-current limiting, followed by shutdown after 5 seconds; reapply input power to recover. Overload also uses constant-current limiting and shuts down the output after 5 seconds. Remove the fault before restoring operation.
Overvoltage protection shuts down the output and requires input power to be reapplied. Overtemperature protection shuts down the output and recovers automatically after the temperature falls. Temperature-related automatic load reduction is stated specifically for the battery load; the main output must still meet the published thermal derating curve.
Battery reverse-polarity protection uses an internal MOSFET, is specified to cause no damage and recovers automatically after the wiring fault is removed. Low-battery cutoff protects against excessive discharge. Observe battery polarity and the separate load and battery terminals.
Form-C Relay Alarms
External alarm-circuit limits
30 VDC maximum; 1 A maximum sink/contact rating
AC-fail relay: TB4: pins 1, 2 and 3; DC-OK relay: TB4: pins 4, 5 and 6; Battery-low / abnormal / disconnected relay: TB4: pins 7, 8 and 9; Charger-fail relay: TB4: pins 10, 11 and 12.
The Form-C contacts require an external voltage source for the monitoring circuit. AC normal closes 2–3 and opens 1–3; battery-only operation opens 2–3 and closes 1–3. DC OK closes 5–6 and opens 4–6 in the listed AC-only, AC-plus-battery and battery-only normal-output states. DC OK is asserted when output voltage is greater than 90% of the rated value.
With a normal connected battery, 8–9 is closed and 7–9 is open. AC-only operation without a battery, or the listed low-battery condition, opens 8–9 and closes 7–9. The alarm table describes low battery as below 30% capacity, while the electrical threshold is the model-specific voltage shown above; do not treat the capacity description as a precision state-of-charge measurement.
A charger fault opens 11–12 and closes 10–12. The specification states relay ON for charger OK and OFF for charger failure. Dashes in the operating-state table do not define an additional contact state.
LED Status and Diagnostics
DC OK is green when the output is normal and off on DC failure. AC Fail is red on AC failure and off when AC is normal. The Status LED is green in float/full-charge indication and orange during CC/CV charging.
Status orange, one blink followed by a pause, indicates discharging. Red blink groups followed by a pause mean: 1=charger failure; 2=battery overvoltage or reverse polarity; 3=battery low or no battery; 4=battery-discharge peak-power timeout; 5=overload or short circuit; 6=overtemperature; 7=timeout.
Battery Temperature Compensation
Factory compensation setting
−3 mV/°C/cell
Selectable compensation
Disabled, −3, −4 or −5 mV/°C/cell
Compensation temperature range
0–40°C; 25°C reference
The supplied NTC sensor connects to RTH+ and RTH− on CN1, pins 3 and 4. Attach the sensor to the battery or its vicinity. The supply can operate normally without the sensor; an open sensor connection is treated as normal temperature and no compensation is applied.
Compensation settings are modified through CANBus. Compensation applies to lead-acid batteries only, not lithium-ion batteries. Below 0°C or above 40°C, the compensation calculation is limited to the respective 0°C or 40°C endpoint; there is no correction at the 25°C reference.
For a selected per-cell slope, the boost-voltage correction is the slope multiplied by the measured temperature difference from 25°C and the number of cells. The catalogue’s 24 V example uses 12 cells, 28.8 V boost and −5 mV/°C/cell, giving 30.3 V at the 0°C endpoint and 27.9 V at 40°C. This example does not replace the selected model’s charging settings.
Power Terminals and Auxiliary Connector
TB1 input terminals: 1=FG protective earth; 2=AC/N; 3=AC/L. TB2 battery terminals: 1 and 2=BAT−; 3 and 4=BAT+. TB3 load terminals: 1 and 2=+V; 3 and 4=−V. Connect the load and battery to their designated terminal blocks.
CN1 is the 8-pin force-button/auxiliary connector, identified in the mechanical table as JS-2008R-4*2-T or equivalent. Pin 1=3.3 V; pin 2=GND; pin 3=RTH+; pin 4=RTH−; pin 5=A0; pin 6=A1; pins 7/8=open for normal operation or short for force start. Follow the manufacturer’s communication instructions for address and control wiring; the 3.3 V pin is not specified here as a general-purpose auxiliary power supply.
Keep the RJ45 signal return and power-output terminals as defined in the pin table. Select conductors, terminal preparation and tightening torque according to the supplied product label and installation manual.
Standard Accessories and Installation Items
Included NTC sensor wire
NSG05C250J5, quantity 1
Included mating wire
JS-2007-2*4-T or equivalent, quantity 1
DIN rail compatibility
TS35/7.5 or TS35/15; rail not included
The NTC sensor-wire drawing identifies UL2468 24 AWG two-conductor cable, a 50 mm lead reference and 7 mm stripped ends. The included mating lead uses UL1007 28 AWG wire with a 50 mm lead reference and 7 mm stripped ends. The customer supplies any extension cable between the mating lead and battery sensor.
SBP-001 is the separately ordered programmer for this CANBus model. Specify the DRS-compatible SBP#2 communication cable and computer connection when selecting programming equipment.
The NTC and mating lead are standard accessories listed with the power supply. The battery, DIN rail and installation wiring must be selected for the actual system.
Environment, Cooling and Derating
Working ambient temperature
−30 to +70°C, subject to derating
Working humidity
20–90% RH, non-condensing
Storage conditions
−40 to +85°C; 10–95% RH, non-condensing
Load-output temperature coefficient
±0.03%/°C from 0 to 50°C
Vibration
10–500 Hz, 5G; 10 minutes/cycle; 60 minutes each along X, Y and Z
Operating altitude / overvoltage category
2000 m / OVC III
Cooling is by free-air convection. In the vertical mounting orientation, the thermal curve shows 100% load from −30 to 50°C, 80% at 60°C and 60% at 70°C. Above 50°C the permitted load decreases along the plotted line.
The 60 Hz input-voltage curve permits 90% load at 90 VAC, rises to 100% at 100 VAC and remains at 100% through 305 VAC. Apply the temperature and input-voltage limits together.
For permanent full-load installation, leave 40 mm above, 20 mm below and 5 mm on both sides. Where the adjacent device is a heat source, the catalogue recommends 15 cm clearance. Keep all ventilation openings clear.
The operating/OVC rating is stated to 2000 m. A general catalogue note gives an additional 3.5°C ambient derating per 1000 m for fanless equipment above 2000 m; obtain manufacturer confirmation before extending the rated installation altitude.
Safety, EMC and Reliability
Safety standards
UL 62368-1; DEKRA BS EN/EN 62368-1; RCM AS/NZS 62368.1; EAC TP TC 004 approved
Fire detection and alarm reference
Compliance to BS EN/EN 54-4
Withstand voltage
I/P–O/P: 4 kVAC; I/P–FG: 2 kVAC; O/P–FG: 1.5 kVAC
Isolation resistance
100 MΩ at 500 VDC, 25°C, 70% RH for I/P–O/P, I/P–FG and O/P–FG
Conducted / radiated emissions
BS EN/EN 55032 (CISPR 32), Class B
Harmonic current
BS EN/EN 61000-3-2
MTBF references
564.7K hours minimum, Telcordia SR-332; 73.3K hours minimum, MIL-HDBK-217F at 25°C
The signal-alarm design references UL 2524, NFPA 1221, BS EN/EN 54-4 and GB17945, with parameters configurable through the communication interface. These component design/compliance statements do not certify a complete alarm or emergency installation.
Immunity references are BS EN/EN 55035, BS EN/EN 61204-3 and BS EN/EN 61000-6-2 (EN 50082-2). Tests list ESD: 8 kV air, level 3, and 4 kV contact, level 2; radiated: 10 V/m, level 3; EFT/burst: 2 kV, level 3; surge: 1 kV line-to-line and 2 kV line-to-chassis, level 3; conducted: 10 V, level 3; magnetic field: 30 A/m, level 4. Performance criterion A is stated.
The catalogue EMC tests mount the unit on a 720 × 360 mm metal plate, 1 mm thick. The supply is a component for installation in final equipment. Confirm EMC performance again with the complete installation.
MTBF values are reliability references under the stated methods and conditions, not a guaranteed service lifetime.
Mechanical Dimensions and Weight
Catalogue dimensions
85.5 × 125.2 × 129.2 mm (W × H × D)
Catalogue unit-weight reference
1190 g
Catalogue packing
1.19 kg; 8 pcs / 12.5 kg / 1.08 CUFT
Case reference: 984G; Dimensional tolerance: ±1 mm.
Mount the unit on an admissible TS35/7.5 or TS35/15 DIN rail as shown in the back-view installation drawing. The illustrated rail is a reference and is not included. Allow access to the input, load, battery, alarm and communication connections.
The single-unit weight is the catalogue PACKING reference per unit, not a measured net or shipping weight. Carton quantity and carton mass are separate packing information.
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