17.3 Protective means for equipment that uses a switching transformer
[Basic requirements]
Equipment with switching transformers capable of outputting power of 15 W or more but without
thermal fuses in those switching transformers shall incorporate protective means, in order to
prevent smoke emission, ignition and fire hazards caused by abnormal overheating as a result of
short-circuiting or semi-short circuiting of the secondary circuits.
[Design standards]
Such equipment shall incorporate circuits for providing overvoltage protection, overcurrent
protection or other means of protection.
Furthermore, the equipment shall also be provided with a current fuse, fusible resistor or other
overcurrent protection devices in the primary circuits of the power supplies.
[Criteria]
Compliance is determined by visual inspection and by testing. Testing applies to areas which cause
the emission of smoke, ignition or fire due to abnormal overheating in the secondary circuits, and is
carried out in accordance with PCSS-Q-07004 "Safety test when short or open circuit occurs in
electrical circuits.