User's Manual

Introduction
Page 6
1 Introduction
The Enraf 973 SmartRadar LT is a radar based level gauge. It is designed to measure the product level in
large storage tanks accurately and reliably.
The following options can be added to the basic SmartRadar:
• One hard alarm output contact, which can be linked to one of the four programmable alarms in the
instrument;
• An Infra-Red connector for the configuration tool 847 Portable Enraf Terminal;
• An intrinsically safe output to connect the 977 Tank Side Indicator.
Additional sensors can be connected to the SmartRadar when the optional ICU_HPI board is installed. This
provides the instrument inputs for:
• Spot temperature element (Pt100);
• HART channel for: Model 762, which is a converter for average product (and vapour) temperature
measurement (via MTT) with optionally an integrated water bottom probe;
• HART channel for: pressure transmitters for HIMS configuration or vapour pressure measurement
and for a side mounted water probe.
Standard, the SmartRadar is provided with Enraf field bus transmission for communication with remote tank
gauging systems. Optionally, the following output signals are available:
• Analog 4-20 mA level output with HART communication for other measured quantities (Enraf field bus
signal also available). This requires the optional ICU_HPO board;
• RS-232C or RS-485 serial communication (Enraf field bus signal not available). This requires the
optional ICU_RS232/485 board.
Basic
973 SmartRadar LT
Optional Hard alarm output contact
Optional IR connector for 847 PET (Portable Enraf Terminal)
Optional I.S. output for 977 TSI (Tank Side Indicator)
Optional input board Optional output board
ICU_HPI board: ICU_RS232/485 board: ICU_HPO board:
- spot temperature element - RS-232C or - HART output and/or
- HART channel for 762 - RS-485 - analog 4-20 mA level output
- HART channel for P1, P3
1.1 Principle of measurement
The radar level gauge is a device that uses high-frequency (10 GHz) electromagnetic waves to determine
the distance from the radar antenna to the product surface.
The electro-magnetic wave is sent into the tank and reflected by the product.
As an electro-magnetic wave travels with the speed of light, this measurement can not simply be done on
the basis of time of flight. Instead, the phase difference between the transmitted and the received signal is
measured. The corresponding travelled distance can then be calculated from this phase relation.
This measurement principle is known as synthesized pulse radar (SPR).