Discount Security Cameras upgraded all of their multi-channel 12V DC power supplies (DPWR910UL, DPWR1820UL & DPWR1824AC-UL) from glass fuses to thermal fuses. This is a great improvement in the products.
The way glass fuses work is that when they heat up (from power overload), the glass contains a thin metal strip that fails (melts apart) at a predetermined amperage which breaks the electrical circuit. Once the fuse is ‘tripped’ the fuse is then non-functional – you just throw it away and that channel of the power supply will not work until you replace the fuse with a new one.
The way thermal fuses work is that when they heat up, two wires inside the fuse will separate and that breaks the electrical circuit. When the fuse cools down, the wires fall back together and the fuse will be functional again – no need to replace the fuse.
The thermal design is a huge improvement, especially when troubleshooting power problems with your CCTV system. When troubleshooting, it is commonplace to go through a cycle of fixing and testing. When using glass fuses each time you test (and fail) it would destroy another fuse. With thermal fuses you can repeatedly test the system without destroying the fuse, which makes the whole process faster and less expensive.