High quality Shutter Sensors magnetic contacts Roller Door Sensor

High quality Shutter Sensors magnetic contacts Roller Door Sensor         Product Description     Overhead roller shutter sensor                                                                          Wider Gap for reduced false alarms                                                                       NC or NO loop.                                                                                   overhead door magnetic contact is for use in the rigorous environments of commercial and industrial installations. Housing: ABS material ; fireproof ABS housing is available on request                                                           Color: white Gap:50-60 mm                                                                                  Overhead door surface mounted contacted with terminals Note:  1. NC--- here means normally closed. When the door is closed,  the contact of sensor is also closed. If a thief  opens the door,  the contact of sensor will be open , then the   alarm will receive  the  signal.  2. NO--- here means normally open. When the door  is closed ,the contact of the sensor will be open. If a thief opens the door , then the contact of sensor will be changed to closed , stimulating  the alarm to work.  3. COM---here means both normally closed and normally open . The contacts of sensor  can be changed each other .