Which grade is higher, Ga or Gb, in explosion protection certification?

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Ga, Gb, and Gc are the protection ratings used for equipment in explosive gas environments, and they are an essential part of the explosion-proof equipment markings. https://pic1.zhimg.com/80/v2-b312db94dfd10a60cca1a161ec5affe8_720w.jpg ※ Ga is equipment for explosive gas environments, featuring a \"very high\" protection level. During normal operation, it does not act as a ignition source in the event of expected or rare failures. Devices with a Ga protection level can be used in Zones 0, 1, and 2. ※ Devices for explosive gas environments of type Gb have a \"high\" protection level. It is not a ignition source under normal operating conditions or expected failure conditions. The Gb protection level can be used in Zone 1 and Zone 2. ※ Gc equipment for explosive gas environments has a “general” protection level. It is not a source of ignition during normal operation, and additional protective measures can also be taken to ensure that no effective ignition occurs in situations where a source of ignition is likely to appear frequently (such as lamp failures). Devices with a Gc protection level can be used in Zone 2. As is well known, Zone 0 is the most dangerous area, and only a protection level of Ga equipment can be used there; therefore, the protection level of Ga equipment is higher than that of Gb equipment.