Explosion-proof heating device for hazardous area - has enclosed display elements indicating operation and is visible through sealed glass window

摘要

The heating device has a display circuit for indicating the operating state of the device. The circuit includes a LED energised via the secondary winding of a current transformer in the heating current network. A further LED or a light bulb is also included in the circuit to indicate when a temp limiter is coupled across the DE or AC voltage respectively. The LED's or the LED and the light bulb are housed within the explosion-proof casing of the heating device, so as to be visible through a sealed glass window. In the case of a three-phase hearing device each phase each phase may incorporate a current transformer with an associated LED.