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Rev. A.1, 8/01 Page- 7
Note that if the door is heavily pre-loaded (by someone trying to pull it open before the Mortise
UnLatch has released it for example), the Mortise UnLatch may not possess enough power to
release the door. This is termed a stall condition for the motor. When a motor is stalled for a
period of time, it can be damaged by heat build up as motors draw heavy current when they’re
not permitted to move. The Mortise UnLatch automatically detects any stall condition that
persists for more than 1.5 seconds and shuts itself off. To operate, the Mortise UnLatch must
simply be triggered again (which is the normal action for anyone who has failed to enter).
4. WIRING
4.1 GENERAL ELECTRICAL CHARACTERISTICS
The Mortise UnLatch is a six wire device. Power (12 or 24VDC depending on the model) is
applied to the red and black wires observing polarity and power should be continuously
present on these wires. If you connect power in reverse, the Mortise UnLatch will not
operate but it will be damaged if left connected for an extended period of time. To
operate the Mortise UnLatch, the trigger wire (orange) is connected to the red wire (+V) via an
external switch. When this connection is made, the Mortise UnLatch will release the door and
keep it released so long as the red and orange wires are connected. When connection between
these wires is broken, the door will be resecured (once it recloses). In certain applications the
door is released all day and secured all night. There is no problem operating the Mortise
UnLatch in this manner (continuous duty) but it is more common for the door to be released for
only a few seconds at a time for controlled entry. This is typically done by relay contacts which
close from an external card reader, digital keypad or keyswitch. The external control device
includes a timing function which will operate the Mortise UnLatch for a few seconds to permit
each entry. Like most conventional electric strikes, the Mortise UnLatch is fail secure which
means that it will maintain the door in a secure position if power is lost. Entry is not possible
(except with a key) but people can, of course, exit by simply turning the door handle or knob
from the inside.
FIG. 7: MORTISE UNLATCH WIRING
WHITE (STATUS: COM)
BLUE (STATUS: N.O.)
CLOSURE
BETWEEN +V IN
AND TRIGGER
RELEASES LATCH
+-
ORANGE (TRIGGER)
GREEN (STATUS: N.C.)
POWER SUPPLY
RED (+V)
BLACK (NEG)
UNLATCH
POWER SHOULD BE CONSTANTLY CONNECTED
DC
In normal operation, the Mortise UnLatch draws about 600 mA @ 12 VDC or 300 mA @ 24VDC
when it operates (the plungers are moving) and a steady 40 mA at all times. Note that regulated
input voltage is not required to operate the Mortise UnLatch. Full wave rectified DC is
acceptable (transformer + bridge rectifier). Power supply surge capacity, however, is ideally
4 Amps @ 12 VDC or 2 Amps @ 24 VDC for best operation. This is because the Mortise
UnLatch’s motor (like all motors) will momentarily draw a lot more current if it has to “work
harder”. This occurs for a very short time at motor start. If power supply surge capacity is
limited, the Mortise UnLatch will still operate, but more slowly. The same condition of high
current draw will occur for a longer period of time if the latch is binding which could be a
permanent condition of the latch or could be because the person trying to enter is pulling on the
door. Again, the Mortise UnLatch will function but more slowly and weakly. If a full capacity
power supply is not practical, a 1 Amp power supply which includes battery backup such as
Securitron’s model BPS-12-1 or BPS-24-1 (with battery) is an equally effective device to power
the Mortise UnLatch as the battery will provide extra surge current as it is needed. Another
point to note is that when one relatively large power supply is serving a number of Mortise