The Hekatron THM 433 is a Wall Mounted Electromagnetic Door Retainer. The THM 433 is used to keep self-closing doorways, such as fire doors, smoke doors and other doors or gates open. The THM-433 must be connected to a smoke detection system, which will break the circuit to de-energize the electromagnet, if a fire occurs. This will allow the door to close, and stop the fire from spreading.
The THM 433 is provided with a spark-suppression diode (free-wheeling diode) to protect the contacts against premature erosion and voltage surges, plus a reverse polarity protection diode.
