Issue
There is a concern about the Amp draw through the SCU's on-board relays using a Von Duprin EL35 door strike
Environment
I/NET site with Access Control
Cause
issue with Von Duprin lock
Resolution
The Von Duprin lock has 2 stages of solenoids:
- The first solenoid is very low impedance (high current)
- The second solenoid is a lower (more typical) current draw and serves to hold the lock after moved by the high current solenoid.
This creates a mechanical movement interval where the locks power requirements are very large while the first solenoid is active.
The Von Duprin power supply has specific specially designed circuitry to accommodate high pulse current output. Altronix also has such a supply especially designed for the Von Duprin lock. Their model StrikeIt1 is rated 24Vdc @ 1 amp continuous - with a special provision for 15 amp surge for 300ms.
The basic operation is as follows - As the standard continuous duty regulator folds back under current limiting, they will momentarily switch on the raw DC from the input bridge rectifier to allow direct current draw from the diode bridge and input power transformer. The combination used in this product accommodates 15 amp for 300 milliseconds. This is applicable to 24V output only and it depends on switching ON the raw DC which is typically setting around 28 volts.
This is an unusual power requirement, and it takes usual power supply to accommodate.
There are two potential solutions:
- Use the Von Duprin power supply to power the Von Duprin locks.
- Use the Altronix StrikeIt1 power supply which was specially designed for the Von Duprin lock
Both of these power supplies have a built in relay that switches the high amp current to the door strike. This power supply relay is the one the SCU relay will fire, thus removing the High Amp draw through the SCU on-board relay
