SARGENT Timer Model - TMR2 Multi-Function - Manual (Page 7)

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© SARGENT Manufacturing Company 2006, 2007
7. USE OF THE MOV (INDUCTIVE KICKBACK PROTECTION)
Note that a loose electronic component has been furnished with the TMR2. This is a metal
oxide varistor (MOV). Its purpose is to absorb inductive kickback if the TMR2's relay is used
to control an inductive load. When an inductive load is switched off by the relay, it emits a
high voltage spike in reverse polarity (kickback). This will considerably shorten the life of the
relay contacts and may also cause inconsistent operation of the TMR2 owing to electronic
noise from the kickback interfering with the TMR2's microprocessor.
Inductive loads possess coils and generally include any electromagnetic device such as
solenoids, motors or electric locks. Installation of the MOV consists of attaching it in parallel
across the power input wires of the inductive load. The MOV is suitable for any inductive
load that operates from 12 to 24 volts AC or DC. If the TMR2 is being used to
control a high voltage device with its own high voltage power supply, the MOV
must not be used as it will burn out. Note that if SARGENT’s 1500 Series
Electromagnetic Lock is being controlled by the TMR2, the MOV is not necessary as the
Electromagnetic Lock has internal kickback protection. The drawing below shows typical
wiring which employs an inductive load, the MOV, a trigger switch and the TMR2 with its
power supply.
FIG. 5: TYPICAL TMR2 WIRING WITH USE OF MOV
NC
NO
C
T
R
F
C
NC
NO
RELAY
DIP SWITCHES
LED
12-24 V
AC OR DC
POWER
SUPPLY
INDUCTIVE
LOAD
MOV
IN THIS CIRCUIT, THE LOAD TURNS OFF WHEN THE TIMEMASTER RELAY ENERGIZES
TRIGGER SWITCH
SARGENT Manufacturing Company • 100 Sargent Drive • P.O. Box 9725 • New Haven • CT 06536-0915
Phone: 800-727-5477 • Fax: 888-863-5054 • Web site: www.sargentlock.com
Founded in the early 1800’s, SARGENT® is a market leader in locksets, cylinders, door closers, exit devices,
electro-mechanical products and access control systems for new construction, renovation, and replacement applications.
The company’s customer base includes commercial construction, institutional, and industrial markets.
© SARGENT Manufacturing Company 2007
ASSA ABLOY is the global leader in door opening solutions, dedicated to
satisfying end-user needs for security, safety and convenience.
TMR2