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 Technical Information Sheet SL36-NPT

 Novaris Pty Ltd ABN: 33 065 427 232 72 Browns Road, Kingston, TAS. 7050 TEL: +61 3 6229 7233 AUSTRALIA FAX: +61 3 6229 9245

Copyright  2000 Novaris E-mail: sales@novaris.com.au 

SURGE PROTECTORS FOR PROCESS TRANSMITTERS

SL36-NPT3/4 SL36-NPT1/2 

Product Description

 Novaris SL36-NPT signal line protectors are designed

for the effective protection against lightning and other

transient overvoltages on process control 4/20mA

transmitters. These units can be readily fitted to field

mounted instruments whilst still maintaining explosion

 proof integrity where applicable. All components in

the SL36-NPT series are passive and the whole unit

may be defined as simple apparatus.

For the protection of the remote end of the circuit at

the RTU Novaris SL1-36 DINsafe signal line

 protectors are recommended. 

Operation

The SL36-NPT is a shunt-connected device. It

therefore inserts no series impedance and does not

effect device calibration or operation. The unit

 provides protection against common mode and

transverse mode disturbances. Common mode

disturbances are typical of lightning induced voltages.

These voltages exist between each signal line and

ground and can have high energy content. For commonmode protection the protector comprises a fast acting,

high-energy, three-element gas arrester connected

 between each line and ground. Most instruments can

withstand common mode voltages of up to 500V.

Transverse mode protection is provided in the first

instance by the gas arrester as primary protection plusa fast acting transient clamping diode, which limits line

to line voltage to 36V, well within the limits of 12V

and 24V instruments.

Installation

Screw the protector into a spare conduit entry on the

instrument body. Connect the flying leads as follows:

 Red to +ve terminal

 Black to –ve terminal

Green/Yellow to earth terminal (frame).

ALL LEADS MUST BE AS SHORT AS POSSIBLE.Do not coil leads, cut them to the minimum length

required.

Specifications

Description: Shunt connected surge protector for4/20mA process instruments.

Protection modes: Transverse and commonmode

Protection stages: Gas arrester/Transorb

Surge withstand: IEEE C62.41 cat, A, B, C AS1768-1991 cat. A, B, C

Surge rating: 20kA for 8/20µs pulse

Transverse mode clamp voltage:36V peak

 Arrester firing voltage: 230V peak

 Arrester residual voltage: 20V peak

Material: nickel plated brass, epoxy filled

Dimensions:

¾” NPT 30 long x 32 diameter, hex 27AF½” NPT 70 long x 39 diameter, hex 34AF

 Approval: AUS Ex2428UEx d ia IIC T4 Class 1 Zone 1

Options

Cat No. Clamp DescriptionSL36-NPT3/4 36V ¾” NPT threadSL36-NPT1/2 36V ½” NPT thread

 Note: Other clamping voltages available on request