Securitron DK-26 User Manual download pdf (Page 4)

PN# 500-16900

Page 3 Rev. D, 12/11

Be sure that your power source is of adequate capacity to operate both the lock and

DK-26. If the installation is "under-powered", the voltage of the supply will drop

rapidly when the lock is energized and this can crash the microprocessor.

3.2 CONNECTING THE KEYPAD CABLE TO THE CPU BOARD

There are 12 color coded wires in the keypad cable. Refer to Figure 3 and connect each wire to

the indicated terminal on the CPU Board. No other connections may be made to these terminals

(except if two keypads are used with one CPU board).

3.3 POWER AND ELECTRIC LOCK WIRING

The wiring scheme for electric lock control varies depending on the type of lock and the desired

control. The following sections provide drawings and explanations for different types. Note that

the DK-26 includes additional options which are covered in Sections 6 and 7.

Note installation of the MOV across the power wires to the lock. The MOV is the 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 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.

3.3.1 AC LOCK WITH AC POWER

A fail secure lock operating on AC is used. This is generally an electric strike. “Fail secure”

means that the lock is secure when it is not powered. Power is applied to release the lock.

Referring to figure 2, select a transformer of the same output voltage as the lock (12 or 24

VAC). Make sure the capacity of the transformer is large enough to operate both the DK-26 and

the lock and that the transformer is UL listed under the UL 294 standard. The two

transformer secondary wires connect to the “AC input” terminals as shown (there is no polarity

with AC). Power from one terminal then goes to the common of relay #1. The NO contact of

relay #1 will power the lock (releasing the door) when a correct code is entered. Note that AC

locks are normally all fail secure. If you come across a fail safe AC lock (secure when powered)

you would merely make the connection to the lock from the NC1 rather than NO1 terminal.

FIG. 2: AC LOCK - AC POWER WIRING

NC1 C1 NO1

AC IN F DC IN /OUT

TRANSFORMER

12 OR 24 VAC

AC FAIL SECURE

LOCK

MOV

1 2 3 4 5 6 7 8 9 ... 22 23

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Securitron DK-26 User Manual Page 4