Page 249 - IPD Product Catalog V17

Lightning & Surge Protection

LIGHTNING AND SURGE PROTECTION

FOR SIGNAL LINES

1 1
Overview

Signal and data lines can be exposed to damaging surges,
just as power circuits are. Signal lines can cross the LPZ
boundaries, so it is recommended to install signal and data
SPDs as per a risk assessment outlined in AS 1768.
Data, signal and communications lines are commonplace
throughout industry and the need for interference free
transmission is vital for the reliability, efficiency and
productivity of industrial processes and
commercial operations.
In information technology systems the main function of
arresters is to protect terminal devices. They can also
reduce the risk of cable damage.

Correct selection of arresters depends on several factors including:

• Lightning protection zone (LPZ) of the installation location • Differential mode and/or common mode protection
• Energy to be discharged • System requirements, e.g. transmission parameters
• Arrangement of the protective device • Adaption to environmental and installation conditions
• Immunity level of the terminal device

Selection and installation of arresters for automation and control systems differs from selections for power supply systems as the conditions in power
systems are generally uniform with a 230/400 V system.

In automation and measuring and control systems the parameters can vary depending upon:

• Voltage (e.g. 0 - 10 V) • Frequency (DC, low frequency, high frequency)
• Current (e.g. 0 - 20 mA, 4 - 20 mA) • Type of signal (analogue, digital)
• Type of transmission (balanced, unbalanced)

These electrical parameters for the ‘useful signal’ to be transmitted may contain the actual information to be transmitted.
To ensure reliability and protection of valuable assets, the required useful signal of the automation, measuring or control system must not be influenced
by lightning currents or transient voltages interference.

Selection

Signal and data protective devices encompass many types of protocol, cable systems and applications.
• Measuring and control systems • Computer networks • Hazardous areas and Ex systems
• Building management systems • Telecommunications systems • Intrinsically safe requirements
• Building automation • Process control systems

Correct selection of surge protection for these systems is critical to ensure interference free transmission of data and uninterrupted processes.

1. Confirm the signal protocol and peak line voltage of the system 3. Confirm the signal current
2. Select the appropriate clamping voltage, Clamping voltage must be 4. Confirm the required signal frequency/data rate
greater than the peaksignalling voltage

At the field device level, solutions are available for mounting locally on sensors etc.

1300 556 601 | ipd.com.au | V17-R05 249