Securitron MSS-1-RT - Manual (Page 5)

PN# 500-16710
Page 5 Rev. A, 03/11
Beyond the simple function of putting the switch into alarm, the MSS has a special remote test
feature which requires an explanation. Putting each switch into alarm does verify that it will go
into alarm if the door opens, but does not verify that it is working in full high security mode. To
explain, the MSS employs two internal reed switches. For it to report secure, both switches
have to be put into the secure mode by the proximity of the magnet pack. If either or both
switches are not in the secure mode, the unit will report an alarm condition. Suppose that one
of the reed switches suffered an internal failure such that it was always in the secure mode. The
MSS would appear to work but with only one working reed it would be functioning as an
ordinary magnetic switch which can be defeated with a single external magnet. The chances
of such failure are extremely low in a sealed unit, but they are not zero and they can be
detected with the MSS’s unique remote test procedure.
The remote test circuit employs three wires. Blue is common and yellow and brown constitute
two separate test points. By applying +12V to yellow, you put one of the internal reeds into the
alarm condition. The output of the MSS will then also be in alarm condition. Next, by applying
+12V to brown, you put the second internal reed into the alarm condition and the MSS should go
into alarm once again. If both tests fail to put the MSS into alarm, it is either entirely defective
or (more likely) there is a problem with its wiring to the alarm panel. If one test fails, the MSS
is operating on a single reed as an ordinary magnetic switch and must be replaced. This test
procedure assures full high security operation of the MSS.
Naturally in an actual installation, the switches are tested simultaneously. All blue, yellow and
brown wires are tied together with like colored wires and connected to a 12V power supply
through two normally open test switches. First one “side” of all switches are tested and then the
second side is tested. You interpret the results as described in the preceding paragraph. Note
that each test point will draw 15 mA for each switch so you need to plan your power supply
capacity by multiplying 15 mA times the number of switches wired together. For example, a 100
switch installation would draw 1.5 Amps during each of the two tests so you should employ a
two Amp supply to have some headroom. Make sure it is a UL listed Class II or Power
Limited power source. Also insure that the normally open test switch contacts are able to
handle the current. Finally, be sure never to perform both tests at the same time or they will be
meaningless and you may overload your power supply.
The drawing on the next page shows typical remote test wiring for three units. Naturally it can
be expanded to any number of MSS switches. Note that the 12V power supply need not be
regulated. Full wave rectified DC power is acceptable. Also, you may realize that the remote
test function energizes small coils within the units which generate a magnetic field to put the
switch into alarm. These coils do not produce any inductive kickback as they are internally
suppressed. There will be no arcing across the test switch contacts.
MSS #1 MSS #2 MSS #3
12 VDC
POWER
SUPPLY
+
BL
U
E
BL
U
E
BL
U
E
YE
L
.
YE
L
.
YE
L
.
REMOTE TEST WIRING SHOWN WITH THREE MSS SWITCHES. ANY NUMBER OF MSS
SWITCHES CAN BE CONNECTED IN THIS WAY. NOTE THE TWO NORMALLY OPEN TEST
SWITCHES. THEY SHOULD BE CLOSED ONE AT A TIME AND ALL MSS SWITCHES SHOULD
GO INTO ALARM TWICE TO PASS THE TEST.
TEST SWITCHES
C
NO
NO
C
B
RN.
B
RN.
B
RN.
6. MAGNACARE  LIFETIME REPLACEMENT WARRANTY
For warranty information visit www.securitron.com/en/site/securitron/About/MagnaCare-Warranty/
PATENT NOTE: T he products discussed in this manual are covered under US patent #5,668,533