Haydon HAY-PSU1612-20A 16 Way 20Amp boxed PSU
- CCTV Lens Guide
- Hard Drive Size Guide
Unless selecting a vari-focal camera (with an adjustable lens) It is important to select the correct camera lens option for where the camera is to be positioned. A smaller lens will give you a wider angle but will be "zoomed out more", while a bigger lens will narrow the angle down and "zoom in more". See below to give you some idea on angles of Megapixel HD Cameras:
| Lens in mm | Approx Viewing Angle (degrees) | Ideal Distance (metres) | Typical usage/notes |
|---|---|---|---|
| 2.8 | 106 | <6 | For seeing as much of the immediate area as possible such as above a doorway/low down/garage soffits (edges can appear slightly warped/distorted) - clearly "zoomed out" |
| 3.6/4 | 83-90 | <12 | A great general purpose option giving great coverage still in the corner of a room or higher up on second floor soffits with less distortion - more of a natural "zoom" |
| 6 | 56 | 6-20 | Narrows down the angle and zooms in to look past the immediate area a little to gain more detail - down a driveway for example from higher up |
| 12 | 24 | 20+ | Zooms in significantly more to look at a gate, entrance or adjascent building |
| 16 | 19 | 24+ | As above but more so |
The amount of hard drive space you require is dictated by how many cameras, as well as their resolution, frame rate settings, and whether you have H.265 encoding enabled or not to save space (We advise turning it on to double the capacity shown below with ease).
Finally, you can often make your storage space last a lot longer by enabling motion-detected recording rather than continuous, especially if there are long periods of no activity (to perhaps double or more these figures again).
|
Resolution (Megapixels) |
Days of storage provided by 1TB per camera (continuous - full 25 frames per second) |
Days of storage provided by 1TB per 4 cameras (continuous - full 25 frames per second) |
Days of storage provided by 1TB per 4 cameras (50% motion- 15 frames per second) |
|---|---|---|---|
| 1 | 44 | 11 | 36 |
| 2 | 22 | 5 | 18 |
| 3 | 17 | 4 | 14 |
| 4 | 11 | 3 | 9 |
| 5 | 9 | 2 | 8 |
| 6 | 8 | 2 | 6 |
| 8 (4K) | 5 | 1 | 4 |
| 12 | 4 | 0.5 | 3 |
As a rule of thumb, we recommend 2 Terabytes for a 4 x 4/5MP HD camera setup, as this should give you approx 2 weeks using H.265 @ 20fps and that is on continuous, not motion-detected recording.
(You may only require the full 25 frames per second on certain cameras if things are fast-moving - ie above a till)
You can also use the Hikvision online calculator to work out what works best for you specifically: https://tools.hikvision.com/ca...
(All of our hard drives come fitted and are CCTV-specific from one of the major brands)
When traditional fuses are being used for overcurrent protection it can only protect once then it must be replaced. The PTC resetable fuse is a new-type of overcurrent protection element which has two functions providing overcurrent protection and automatic reset.
The overcurrent protection PTC element is serially connected to the circuit and under normal circumstances it provides a low resistance state and can ensure the normal working of the circuit. If a short circuit or unusually high current occurs, the PTC fuses cut in to reduce the voltage down to a trickle thus preventing damage and protecting the equipment.
The PTC fuse will automatically reset once the fault in the overcurrent is removed. The PTC elements will automatically return to its low resistance state, which not only avoids maintenance or replacement but also avoids a continuously circulating switching state which can cause circuit damage.
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