Issue link: https://resources.mouser.com/i/1442856
| 9 | Figure 6 Model HCTSM8 Series has been fully validated BMS Transformer Safety Testing The issue of ensuring that the transformer's insulation will remain intact from the tape in which it is delivered to the board and during the lifetime of the application is resolved by complying with accepted industry standards. Bourns designed and tested its Model HCTSM8 series to survive identified solder reflow conditions and can be reflow soldered three times without degradation of the insulating wire. The insulation strength was tested using a Hi-POT tester applying 4kV rms for up to 60 seconds. Shown in Figure 7 is the criteria Bourns used when it defined the electrical isolation specification. Determining the Overvoltage Category depends on where the power supply is located. If there is no risk of a transient from the mains hitting the power supply, such as where the voltage source is located relative to the battery, then the application may be categorized as Category I. If there is an isolated connection to the mains supply, it is permitted to move from Category II to Category I. The Hi-POT test is used to check the solid insulation in the transformer but it can also be used to verify that the clearances comply with the standard. Any signs of arcing or corona discharges will be a clear failure. The Model HCTSM8 is designed for 800V rms at a 2000m altitude. For higher altitudes, the working voltage must be derated as the breakdown voltage or corona of air decreases as the air becomes thinner. Figure 7 Decision flowchart specifying Model HCTSM8 isolation test voltage