OM1561 ISSUE 3 PAGE 4 of 11
common is also buffered. The buffers allow long cables and low input impedance data acquisition
systems to be used. The load should not be less than 10kohm resistance or greater than 2000pF.
The output common is referenced to the internal chassis ground.
5
CONNECTORS
Each
Mag
-03 sensor is connected to one of the eight Hirose 10-pin connectors on the front panel. The
filtered and buffered sensor outputs are available through two 37-way Cannon D type connectors with
four sensors being allocated to each connector. A nine-pin Cannon D type connector is available for
connecting external temperature sensors and the output signals from these are linked internally to the 37-
way connectors.
6
CABLES
Cables can be supplied to connect any of the
Mag
-03 series of sensors to the
Mag
-03-OCTO-PSU.
Details are given in the operation manual for the sensor. The cables carry the supply voltage to the
magnetic field sensor with the 0V connected through the screen. Analog signals are returned via three
conductors and the analog return is via a separate conductor.
The maximum cable length of 600 metres is derived from the following considerations:
(a)
Above this length the positive supply current of up to 30mA will produce a 1.5 V voltage
drop which may restrict the analog output swing especially where a low voltage supply is
used.
(b)
Above this length the maximum capability for capacitance loading of the magnetic field
sensor output will be exceeded.
Cables other than those provided by Bartington Instruments should generally conform to the
specifications given and a screened type is essential if low noise performance is to be achieved. An
example of an alternative cable is Belden Type 9536 for use in protected conditions, e.g. ducts etc.
7 ANALOG VOLTAGE MEASUREMENTS
To obtain the full precision of the magnetic field sensor the analog outputs should be connected only to
analog inputs which have an impedance greater than 10 k
Ω
.
8
Mag
-03-OCTO-PSU WITH
Mag
-03 SERIES SENSORS
Use of the
Mag
-03-OCTO-PSU power supply eliminates any problems which may be encountered in
providing a suitable isolated power source for an array of sensors. The unit also provides additional
filtering of the analog signals to improve the signal to noise ratio. The high pass filter sections can be
selected to provide either a dc or ac response.
