Comparison of SWM and Molded Wirewound Resistor
The advantage of Anti-suge Wirewound MELF Resistor, compare to Molded Wirewound Resistor
In some industrial control equipment or automotive electronics, you may occasionally see customers using molded wirewound resistors. It encapsulates the outside of the wirewound resistors with plastic to achieve the surface-mounting effect, eliminating the cost of insertion.
Firstohm Anti-Surge Wirewound MELF Resistor (SWM) can be surface-mounted on the PCB directly, and are better than molded wirewound resistors in terms of price and performance of the same sizes.
★ The specifications comparison of Firstohm's Anti-surge Wirewound MELF Resistors (SWM) and molded wirewound resistors:
1.)Both resistors are close in size for the same power, so they can share the same PCB. The schematic diagrams of the copper foil size and the resistor body are shown below. This is the simulated position after mounting the resistors on the same PCB (WSC4527 on the right side is shown bottom facing up to help compare the locations of PCB solder joints and resistor pins).
2.)Surge test: After running surge tests of 1.2/50μs and a voltage of 3KV 50 times, the resistance value of SWM200 remains normal with no change, whereas WSC4527 was burned after one test (figure on the right).
3.)Flameproof Safety: When applying 30 times the rated power directly to both ends of the resistors, SWM200 inner got burned and fused, but no flame appeared, while the WSC4527 caught fire and continued producing flame for 7 seconds. (Top: SWM200; bottom: WSC4527)
SWM (Anti-surge Wirewound MELF Resistors) are applicable for pre-charge resistors, discharge resistors, soft-start resistors, and so on.
- Telecommunication (Base stations)
- Power & Energy
- Industrial Equipment
★Advantage of SWM series :
1.SMD enabled structure
2.Enhanced weld spot is reliable against high surge
3.Flameproof multi-layer coating meet UL94 V-0
4.Mechanical strength against thermal shock & vibration
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