Why should moisture-proof electric heaters be installed in high-voltage distribution cabinets

In addition to circuit breaker switches, PT, CT, relay protection, etc., a cast aluminum electric heating plate or moisture-proof electric heater is often installed in the cable compartment of the 0kV high-voltage switchgear, and a condensation controller is also used in conjunction. So what is the effect of installing moisture-proof electric heaters on high-voltage switchgear?
Due to the high voltage of the 10kV high-voltage switchgear, the insulation requirements for the exposed live parts in the air are very high. Once the air is too humid or there is water on the surface of the live parts, it is easy to cause creepage and flashover accidents. To avoid such faults, heating plates are often installed at the bottom of the switchgear or cable compartment to achieve moisture removal. Because the inflatable cabinet adopts a fully insulated and fully enclosed structure, there are no exposed live parts in the air, so there is no need to install a moisture-proof electric heater.
The on-site humidity is high, with significant temperature changes, and there is even water accumulation at the bottom of the switchgear. If the switchgear is installed in the basement, it is also necessary to install a moisture-proof electric heater