Omega Vehicle Security PSW490B, PSW790B manual Introduction

INSTALLATION AND MAINTENANCE OF THE DSW490B AND DSW490B SERIES OMEGA® SNAP ACTION SWITCHES

FOR DIFFERENTIAL PRESSURE CONTROL

INTRODUCTION

The OMEGA differential pressure switch is a precision built U.L. approved control device which features a mechanical snap action switch. Controllers are available for operation on vari- ous pressure differentials with fixed or variable switching differentials. The standard electrical switch is SPDT and is available with various electrical characteristics.

Two SPDT switch elements mounted together are available. Various wetted material construc- tions for compatibility with a wide range of pressure media may be obtained.

The snap action differential pressure switch is furnished in the standard NEMA 4/4X and explo- sion proof NEMA 7 and 9 enclosure styles. Both enclosures are epoxy coated aluminum castings.

INSTALLATION

These controls are precision instruments and should never be left with internal components exposed. During installation insure that covers are in place and conduit openings are closed except when actually working on the control.

MOUNTING DSW490 AND DSW790 SERIES There are three holes external to the enclosure for surface mounting. Location of these holes is shown on the general dimension drawing. They may also be mounted directly on pressure line using the pressure connections.

ELECTRICAL CONNECTIONS

Remove cover

DSW490 Series – two screws hold cover to enclosure

DSW790 Series – cover unscrews

CONDUIT CONNECTIONS

Note – It is recommended that Teflon® tape or other sealant be used on conduit, bushing or plug threads to ensure integrity of the enclosure.

DSW490 series standard – one 3⁄4 NPT conduit hole right side.

DSW790 series standard – two 3⁄4 NPT conduit holes with one permanent plug. NEMA 7 & 9 enclosures require proper conduit seals and breathers as per the National Electrical Code.

DSW490 SERIES

SPDT – Wire directly to the switch according to circuit requirements.

2-SPDT– Dual switching elements consist of two SPDT switches mounted together in a bracket. Switches are calibrated to have simul- taneous operation within 1% of range either on increasing or decreasing pressure but not in both directions. Wire directly to the front and rear switch according to circuit requirements. Leads are provided on rear switch color coded

as follows:
Common	– White
Normally Closed	– Red
Normally Open	– Blue

When hermetically sealed switch element(s) are supplied, the lead color coding is as follows:

Common	– White
Normally Closed	– Red
Normally Open	– Blue

DSW790 SERIES

SPDT – Wire directly to the switch according to circuit requirements.

2-SPDT– Wire to front switch terminal block (left) and rear switch terminal block (right) as marked. Strip insulation 5⁄16˝, insert in proper terminal connector and tighten clamping screw to secure.

ADJUSTMENT OF SETPOINT

DSW490 & DSW790 Series – A single setpoint adjustment nut (7⁄8˝) is located centrally at the bottom on the inside of the enclosure.