Assa DK-26 manual DC Lock AC Power Wiring, DC Lock with DC Power

Rev. A.2, 10/03 Page-6

reduce the switching life of the relay. The arc also creates electronic noise which could cause the microprocessor to malfunction. The MOV should be spliced into the lock power wires as close to the lock as possible. Some DC electric locks have internal kickback protection including all Securitron Magnalocks. You don’t need the MOV for these locks but if you are not sure, it does no harm to install the MOV so long as the lock power is in the 12-24 volt range.

FIG. 4: DC LOCK - AC POWER WIRING

TRANSFORMER

12 OR 24 VAC

	AC
	IN
	F
	DC IN
+	/OUT

	NOTE: MOV NOT REQUIRED IF
	SECURITRON MAGNALOCK IS USED
NC1 C1 NO1	IF FAIL SECURE
		+	DC FAIL SECURE
			OR FAIL SAFE LOCK
IF FAIL SAFE	MOV

3.3.3 DC LOCK WITH DC POWER

Select a power supply of the same voltage as the lock (12 or 24). Make sure the capacity of the supply is large enough to operate both the DK-26 and the lock. The DK-26 does not require regulated power but certain specialized electric locks do, so follow the rule of matching the power supply to the requirements of the lock.

DC locks come in “fail secure” and “fail safe” versions. A fail secure lock is secure when not powered and a fail safe lock is secure when powered. All magnetic locks are fail safe. Figure 5 shows correct wiring. The positive DC terminal connects to the common of relay #1 and either the NO1 terminal (if the lock is fail secure) or the NC1 terminal (if the lock is fail safe) connects to the lock’s positive power input. This is shown in dotted lines. You only connect one of these two terminals. Note that some DC locks are polarized and you must be sure to connect the lock power wires correctly to positive and negative. Others are not polarized and it doesn’t matter which way they are connected. Consult the lock instructions.

Note installation of the MOV across the power wires to the lock. The MOV is the small black disk shaped component furnished loose with the DK-26. Its function is to absorb inductive kickback from the lock’s coil. Without the MOV, this kickback voltage will arc over the relay contacts and reduce the switching life of the relay. The arc also creates electronic noise which could occasionally cause the microprocessor to malfunction. The MOV should be spliced into the lock power wires as close to the lock as possible. Some DC electric locks have internal kickback protection including all Securitron Magnalocks. You need not employ the MOV for these locks but if you are not sure, it never does any harm to install the MOV so long as the lock power is in the 12-24 volt range.