SARGENT Timer Model - TMR2 Multi-Function User Manual

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ASSA ABLOY, the global leader in door opening solutions

A7842A

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

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.

ASSA ABLOY is the global leader in door opening solutions, dedicated to

satisfying end-user needs for security, safety and convenience.

TMR2