E
PI
S
ENSOR
2
U
SER
M
ANUAL
D
OCUMENT
305801,
R
EVISION
A
Dynamic signals increase
instantaneous
power consumption. A typical rule of thumb is that for every 1g
increase in input signal, per axis, power consumption increases by about 150 mW. At the absolute
highest drive levels: 4g simultaneously on each of the three axes (unheard of from natural seismic
sources), this excess power consumption would amount to about 1.8W. Naturally, dynamic signals
impose lower mean energy demands. Also, exact temporal correlation between signals on the three
axes is very unlikely. The absolute maximum dynamic input power is almost certainly lower than 1.8W.
As such, the maximum input power requirements, quiescent plus dynamic, is expected to be under 2W.
As such, a low impedance, 2W power supply is sufficient for the EpiSensor2.
Like most analog sensor products, the power input has a moderate level of input capacitance (a few tens
of microfarads). Any competent power source should be able to provide the instantaneous inrush
currents (a few amps over a few tens of microseconds) required to charge these capacitors. Battery
power is ideal. Also, the EpiSensor2 has been fully tested using the integral sensor power supplies
provided by the Quanterra Q330-series, and Kinemetrics Rock-series digitizers.
Although the sensor electronics employ multiple stages of power supply (noise) rejection, it is always
best to use clean, well-regulated input power.
Thermal Isolation
In order to generate the highest quality data (with low noise and drift at low frequency), the EpiSensor2
should be operated in an environment with high thermal stability. At a minimum, the sensor should be
covered with a foam box in order to reduce the effects of air flow around it. Higher levels of thermal
isolation can be achieved by increasing the effective thermal mass of the instrument. Among the options
for this are sand-packing and the use of interlocking “water bricks”. Please contact Kinemetrics to
discuss the technical details related to increasing thermal isolation.
Page 14
August 2015