Valeport Ltd © 2019
0803805i - Model 803 ECM
Page 4
1. Introduction
This document covers the operation of the Valeport Model 803 2 axis ROV Electromagnetic Current Meter.
The instrument may be supplied with Titanium or Acetal underwater housings in a choice of configurations,
and with a choice of communications options. This manual describes the operation of all versions.
The Model 803 ROV Current Meter is a unique instrument, providing ROV pilots with relative water velocity
data in real time. It may be fitted to ROV’s to provide actual through the water speeds, or fitted to Tether
Management Systems to give a measurement of local flow conditions.
The Model 803 consists of a Valeport 2 axis electromagnetic flow sensor, with processing electronics capable
of giving a variety of output formats for easy interface to almost any system.
The sensor should be mounted in clear flow on the ROV or TMS. When power is applied to the sensor, it
measures the water velocity in 2 axes across the sensor surface. The data is updated at regular intervals (user
selectable), to provide X and Y axis flow information: the X axis is the flow across the vehicle and the Y axis is
flow into the vehicle.
The lightweight design of the instrument leads to minimal effect on the vehicle balance, yet permits a depth
rating of up to 3000m (Titanium version).
Available as a complete self-contained instrument, or with a separate sensor and electronics package, or even
as an OEM system, the Model 803 will appeal both to operators who wish to improve their existing vehicles,
and to manufacturers who want to offer it as an additional item in the sensor package.
1.1. Description
The system comprises the following:
·
Electronics housing containing the system electronics
·
EM sensor mounted on the electronics housing.
Or
·
Electronics housing containing the system electronics
·
EM sensor mounted separately from the electronics housing
Or
·
An OEM system
The flow is measured by a Valeport Series 800 2 Axis Electromagnetic sensor that uses the Faraday principle
to measure the flow past the sensor in two orthogonal axes. The magnetic field is generated within the
sensors by a coil, and the electronics detects the signal generated across two pairs of electrodes, one pair for
each axis.
The electronics carry out all the signal detection and processing, including digital filtering and power/data
isolation, and data output in digital format, in millimetres per second, metres per second or knots. The
calibration is held within the electronics. An optional analogue output signal is also available.
