Guralp Systems CMG-3ESPCD User Manual
Page 10
CMG-3ESPCD Digital Broadband Seismometer
Installing the 3ESPCD
5. Within the next seven seconds, press any key to bring up the disk menu.
6. Key
to reset the disk.
7. When the reset is complete, remove the disk.
You will now be able to download data onto the disk when required.
3.1.6 Power supply
The sensor requires a 12 V power supply, which it obtains through the DATA
OUT port. You may wish to terminate the supplied power cable in order to
connect a 12 V power source to this connector: it is supplied with bare ends.
Using a 12 V, 25 Ah sealed heavy-duty lead-acid battery, you should expect
the instrument to operate for around a week without recharging.
A power management module can be installed as an option, which allows the
3ESPCD to operate from a 10 – 15 V supply range. This module also cuts the
input power to the sensor electronics if it drops below 10.5 V, to minimize
discharge from battery-operated installations.
The 3ESPCD draws a nominal current of 200 mA from a 12 V supply when in
use. During locking and unlocking of the sensor masses, this current rises
briefly to 750 mA. It is recommended that you carry a spare 12 V battery
when visiting an installation for maintenance, in case the sensor needs to be
moved and the on-site batteries no longer have sufficient charge to perform
the locking procedure.
3.2
Installation notes
The goal of any seismic installation is to ensure that wave-trains arriving at
the instrument accurately reflect the internal motion of subsurface rock
formations. To achieve this, the seismometer and its emplacement need to be
considered as a mechanical system, which will have its own vibrational
modes and resonances. These frequencies should be raised as high as
possible so that they do not interfere with true ground motion: ideally, beyond
the range of the instrument.
In particular, the sensor needs to be protected against environmental factors
such as
•
fluctuations in temperature,
•
turbulent air flow around walls or trees, or around sharp corners or
edges in the immediate vicinity of the sensor;
•
vibration caused by equipment in or near the installation, particularly
computer equipment; and
•
vibration caused by heavy machinery (even at a distance), or by
overhead power lines.
10
Issue B - November 2013