Specifications

Level One: Protege GX Installer Study Guide | August 2013 117
Electromagnetic spikes can affect normal system operation and in some cases, damage hardware. You must
use a diode every time a coil, lock, or relay, is controlled.
Waveform with a diode
Waveform without a diode
When the lock is de-energized from 24VDC, the diode absorbs the "Inductive-Kick". All the energy that the locks
coil has to "free" is absorbed by the diode. When the lock is de-energized from 24VDC, there is no diode to
absorb all the energy that the coil has accumulated. This energy has to go somewhere, in this case, there is no
diode to absorb the energy, so it goes in the cable. Note that voltage goes as low -300VDC. These high spikes
can cause electromagnetic disruptions and may affect the normal operation of the system. Even worse, it may
damage equipment that is not protected by a diode.