Dataline Surge Protection Overview

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Copyright © 2011 Citel Inc. USA, Used with permission

Data Line Surge Protection Overview

Introduction

Telecommunication and data transmission devices (PBX, modems, data terminals, sensors, etc…) are increasingly more vulnerable to lightning induced voltage surges. They have become more sensitive, complex and have an increased vulnerability to induced surges due to their possible connection across several different networks. These devices are critical to a company’s communications and information processing. As such, it is prudent to insure them against these potentially costly and disruptive events. A data line surge protector installed in-line, directly in front of a sensitive piece of equipment will increase their useful life and maintain the continuity of the flow of your information.

Technology of Surge Protectors

All Citel telephone and data line surge protectors are based on a reliable multistage hybrid circuit that combines heavy duty Gas Discharge Tubes (GDTs) and fast responding Silicon  Avalanche Diodes (SADs). This type of circuit provides,

• 5kA Nominal Discharge Current (15 times without destruction per IEC 61643)
• Less than 1 nanosecond response times
• Fail-safe disconnection system
• Low capacitance design minimizes signal loss

Parameters for Selecting A Surge Protector

To select the correct surge protector for your installation, keep the following in mind :

• Nominal and Maximum Line Voltages
• Maximum Line Current
• Number of Lines
• Data Transmission Speed
• Type of Connector (Screw Terminal, RJ, ATT110, QC66)
• Mounting (Din Rail, Surface Mount)

Installation

To be effective, the surge protector must be installed in accordance with the following principles.

• The ground point of the surge protector and of the protected equipment must be bonded.
• The protection is installed at the service entrance of the installation to divert impulse current as soon as possible.
• The surge protector must be installed in close proximity, less than 90 feet or 30 meters) to protected equipment. If this rule cannot be followed, secondary surge protectors must be installed near to the equipment.
• The grounding conductor (between the earth output of the protector and the installation bonding circuit) must be as short as possible (less than 1.5 feet or 0.50 meters) and have a cross sectional area of at least 2.5 mm squared.
• The earth resistance must adhere to the local electrical code. No special earthing is necessary.
• Protected and unprotected cables must be kept well apart to limit coupling.

STANDARDS

Test Standards and installation recommendations for communication line surge protectors must comply with the following standards :

• UL497B : Protectors for Data Communications and Fire-Alarm Circuits
• IEC 61643-21 : Tests of Surge Protectors for Communication Lines
• IEC 61643-22 ; Choice/Installation of Surge Protectors for Communication Lines
• NF EN 61643-21 : Tests of Surge Protectors for Communication Lines
• Guide UTE C15-443 : Choice/Installation of Surge Protectors

Special Conditions : Lightning Protection Systems

If the structure to be protected is equipped with a LPS (Lightning Protection System), the surge protectors for telecom or data lines that are installed at the buildings service entrance need to be tested to a direct lightning impulse 10/350us wave form with a minimum surge current of 2.5kA (D1 category test IEC-61643-21).

For a pdf copy of this post click here.

Prevent Overflow – Duplex Lift Station Back-Up Pump Controler

The DR1920 Back-Up Pump Control is a compact DIN rail mounted unit used to monitor
a backup High-High Level Alarm in a tank or wet well and to start up to two pumps when the High-High Alarm switch closes.dr-seriessm

It prevent overflows in situations where the primary level control system fails.

When the High-High Alarm switch in the tank or well closes, the DR1920 closes a relay that starts Pump 1 and starts an internal Timer 1. When Timer 1 reaches its set time, and the High-High Alarm switch is still closed, Pump 2 is started.

Pump 1 and Pump 2 will run until the High-High Alarm switch opens. When the
High-High Alarm switch contact opens, Timer 2 is started and both pumps continue to run until Timer 2 reaches its set time.

If the High-High Alarm switch opens during the Timer 1 interval, Timer 2 is started when the High-High Alarm switch opens. Pump 2 is not started and Pump 1 will run until Timer 2 reaches its set time. Timer 2 is set by the user to lower the level ito the desired low level.

The DR1920 also has provisions to alarm on a switch opening.

ALARM SWITCH MONITOR

The DR1920 monitors the open or closed status of a switch contact that is already
wired into a control system. This switch may have any of several voltages that are
used to control the pump system. In addition, if the primary control system fails, the normal voltages may not be present.

The DR1920 is wired across the alarm switch contacts and uses a unique circuit
that measures the impedance present between the switch contacts.

When the DR1920 senses a low impedance, it begins its control function, regardless of any absence or presence of voltage across the switch contacts. This feature allows the
DR1920 to be wired in parallel across the switch contacts without regard to the
existing control system, permitting simple installation in existing systems.

For situations where the existing wiring prevents this circuit from being used, an
isolated contact must be provided. A second input, which requires an isolated contact or
open collector transistor (optical isolator) is also provided.

A Reset input is provided to stop the pumps and reset the timers. It requires a contact
closure or open collector transistor which will conduct. Since the Back Up Pump Control is used
only when there is a problem with the primary control, the digital alarm inputs, as
well as the reset inputs, are provided to allow the periodic exercising of the system
to verify functionality.

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