A monitoring system includes at least one partial discharge sensor. Fundamental molecular vibration modes of target contaminants present are briefly activated after the surface has been driven out of thermal equilibrium. The duct has a collision avoiding portion guiding a blower motor of the blower in an up-down direction or a side direction of the electric storage unit when the blower motor is moved toward the electric storage unit upon application of an external force. Therefore, multimedia terminals and normal telephony terminals can perform a data exchange through the switching resources controlled by the multimedia controller.