Letzte Aktualisierung: 27. September 2026
schnelle Antwort: CCTV power supply selection for a multi-camera 12V system must start with the exact camera voltage range, worst-case simultaneous current, startup and infrared-load peaks, longest-cable voltage drop, required backup time, and enclosure temperature. The WEHO SC-120-12 used in this worked example provides a 13.8V main output rated up to 8A and a separate 13.4V/0.5A charging output. It is not a universal replacement for every device marked “12V”: confirm that every connected load accepts 13.8V and validate the complete installation before release.
For a security integrator, a power-supply decision is not simply “camera wattage × quantity.” It is a system design covering the supply, conductors, branch protection, battery, cabinet, ambient temperature, and every camera’s day/night operating state. The WEHO SC security power-supply range includes battery-charging designs, while PoE cameras require a different power path through a compatible switch or injector.
This revision replaces the older article’s generic sizing rules with an exact-model example. The product image is controlled by the enterprise-drive SC-120-12 photograph and current SC-120 specification. The two application images are materially different illustrative preparation environments: they show the source-controlled SC-120-12 during protected, unwired installation-fit planning at a logistics perimeter and de-energized visual service preparation on a parking-garage bench. Neither image claims live CCTV operation, a recorded electrical test, or a completed customer installation.
Build a worst-case camera load schedule
Record each branch by model, accepted input-voltage range, normal current, infrared-on current, heater current, pan/tilt/zoom peak, cable length, conductor size, and allowed voltage at the camera. Use the highest simultaneous operating state that can actually occur—not the average printed on a recorder dashboard.
The table below is an illustrative six-camera worksheet. It is not a customer installation or a promise that these loads will fit every SC-120-12 deployment.
| 13.8V-compatible branch | Menge | Illustrative worst-case current | Extended current |
|---|---|---|---|
| Fixed cameras with infrared on | 4 | 0.75A each | 3.00A |
| PTZ cameras during movement | 2 | 1.50A each | 3.00A |
| Controller, relays and monitoring | 1 group | 0.50A | 0.50A |
| Illustrative simultaneous total | 6.50A |
The current enterprise-drive SC-120 sheet lists the SC-120-12 main output, CH1, at 13.8V and 0–8A. A 6.5A worksheet total is below that nominal current, but the difference is not automatically a safe engineering reserve. Measure camera startup, PTZ stall behavior, infrared switching, enclosure temperature, and any derating stated for the exact revision. If cameras require tightly regulated 12.0V and do not accept 13.8V, use an appropriate regulated branch or choose a different architecture.
Calculate voltage drop at the farthest camera
During unwired fit planning, this illustrative image places the exact source-controlled SC-120-12 in the dry protected interior of an open weatherproof cabinet at a logistics perimeter. The five-position amber terminal guard and separate factory-fixed lead harness remain visible, but no field conductors are attached; the scene does not claim live CCTV operation or a completed test. Long low-voltage runs can make a correctly sized central supply look unreliable at the camera, so calculate each branch using the complete outbound-and-return loop resistance. A simple DC estimate is:
Voltage drop = branch current × loop resistance
Use conductor resistance at the expected temperature and include connectors, fuses, distribution blocks, and shared return paths. Then confirm the voltage directly at the farthest camera with infrared on and PTZ motion active. Increasing the supply voltage without confirming the camera’s allowed range is not an acceptable fix; it can overvoltage a short branch while a long branch still performs poorly.
The logistics-yard scene above is an unwired installation-fit illustration. It shows the exact SC-120-12 staged inside the dry protected interior of an open weatherproof cabinet, with the five-position amber terminal guard and separate factory lead harness visible. No field conductors are attached; the image does not claim live CCTV operation, weather-exposure approval, a recorded test, or a completed customer installation. Enclosure rating, surge strategy, grounding, and branch protection remain project responsibilities.
Treat backup time as a measured system requirement
The SC-120-12 specification lists a separate charging output, CH2, at 13.4V and 0–0.5A, plus a low-battery cutoff range of 9.5–11V. That charging branch is not an extra 8A camera output. Battery selection must account for chemistry, permitted charge profile, required autonomy, depth of discharge, age, temperature, cable losses, and end-of-life capacity.
Avoid estimating runtime by dividing the battery’s amp-hour label by the camera current and treating the answer as guaranteed hours. Instead:
- Measure the complete DC load in its worst operating state.
- Select a compatible battery and charging arrangement using the exact SC-120 revision and battery-manufacturer limits.
- Define the minimum acceptable end-of-life capacity and cutoff behavior.
- Perform a controlled mains-failure test at commissioning.
- Record the achieved runtime and schedule periodic battery tests.
The parking-garage image shows the source-controlled SC-120-12 lying de-energized on a stainless service cart during visual service preparation. Its shallow 159 × 98 × 38 mm body, five-position amber terminal guard, and separate fixed lead harness are visible; the loose cable gland and caliper case are context and scale props, not documented measurement results. This indoor bench composition is deliberately different from the outdoor logistics cabinet and does not claim live CCTV operation, an energized test, a passed commissioning result, or a completed customer installation.
Verify input selection, terminals and mechanical fit
The current SC-120 sheet identifies selectable 90–132VAC and 180–264VAC input ranges. This is not a cue to guess the selector position. Isolate the system, inspect the exact ordered unit, confirm the site supply and selector setting, and follow the supplied instructions before energizing. A selector error can damage equipment or create a hazard.
The same sheet gives a 159 × 98 × 38 mm mechanical envelope. These dimensions do not include cable bend, fuse holders, battery, touch protection, service access, or ventilation space. Use the mechanical drawing and verify the real cabinet layout before drilling or ordering an enclosure.
The diagram summarizes the exact values used in this worked example. It is a selection reference, not a wiring schematic. Terminal assignments, conductor sizes, protection, torque, earthing, and battery polarity must come from the exact ordered documentation and the project’s electrical design.
Separate direct low-voltage CCTV from PoE design
A direct 12V camera branch and a PoE camera are not powered in the same way. For PoE, calculate the switch or injector’s total PoE budget, per-port class, cable loss, uplink and recorder behavior, and the AC or DC backup feeding that equipment. Do not place an SC-120-12 output directly onto Ethernet conductors unless a compliant PoE conversion stage is part of the design.
Hybrid sites may use both architectures. Keep the load schedules separate, then combine them only at the upstream backup-energy calculation. This prevents a common procurement error: adding PoE camera watts to a 13.8V output budget without accounting for the PoE conversion equipment.
Commission every branch under real operating conditions
Before handover, verify the input setting, open-circuit output, loaded output at the supply, loaded voltage at the farthest camera, total and branch current, infrared transition, PTZ movement, battery switchover, low-battery behavior, enclosure temperature, and recovery after mains returns. Inspect polarity, strain relief, touch protection, fuse coordination, labeling, and grounding.
Document the exact product suffix and revision in the project BOM. A similar-looking SC model or a different voltage suffix must not be substituted solely because its enclosure resembles the approved unit.
Wichtige Erkenntnisse
- CCTV power supply selection must use worst-case simultaneous current, not average power or an arbitrary multiplier.
- The worked SC-120-12 example is a 13.8V/8A main-output design; confirm every camera’s allowed input range before using it.
- CH2 is a 13.4V/0.5A charging output, not a second high-current camera bus.
- Calculate voltage drop on the full cable loop and verify the farthest camera during infrared and PTZ peaks.
- Validate backup runtime by test, including battery aging and temperature, rather than relying on amp-hour division alone.
- Confirm the AC input selector, exact revision, terminal drawing, protection, and 159 × 98 × 38 mm fit before energizing.
Abschluss
A reliable multi-camera system comes from an auditable load schedule, voltage-drop calculation, compatible backup design, and measured commissioning results. SC-120-12 is a concrete product to evaluate when a project’s loads accept its 13.8V main output and its charging behavior fits the battery plan. Provide WEHO with the camera schedule, cable lengths, site input, enclosure conditions, autonomy target, and approval requirements so the exact model and revision can be checked before purchase.
Product and specification sources
Häufig gestellte Fragen
Is SC-120-12 a regulated 12.0V camera power supply?
The current SC-120 sheet lists the main output at 13.8V, up to 8A. Confirm that every connected camera and accessory accepts 13.8V; do not assume that every device marketed as 12V is compatible.
Can the 13.4V/0.5A output power more cameras?
No. CH2 is the listed battery-charging output. Treat it as part of the backup design, not as another 8A camera-output channel.
How should an integrator size a central CCTV supply?
Add worst-case simultaneous branch current, including infrared, heaters, PTZ movement, controls and startup behavior; then evaluate cable drop, temperature derating, protection and measured commissioning results.
How is battery backup time verified?
Choose a compatible battery and charge profile, allow for temperature, aging and permitted depth of discharge, then perform a controlled mains-failure test at the required load.
Does SC-120-12 power PoE cameras directly?
Not by itself. PoE cameras require a compliant PoE switch, injector or conversion stage with its own per-port and total power budget.
