Operator’s Manual
EAR99 technology subject to restrictions on copyrights page.
5
Introduction
The HVFO108 High Voltage Fiber Optically-isolated probe is an affordable, optimally designed
probe for measurement of small signals floating on an HV bus in power electronics designs, or
for EMC, EFT, ESD, and RF immunity testing sensor monitoring. It far surpasses the
measurement capabilities and signal fidelity of conventional high attenuation, high voltage
differential probes and acquisition systems that rely on galvanic channel-channel and channel-
ground high voltage isolation. Furthermore, it mitigates the need to rely on dangerous test
setups that require floating the oscilloscope and probe.
Key Features
•
150 MHz bandwidth
•
35 kV common-mode voltage rating (fiber optic isolation)
•
Signal voltage measurement range from +/-1 V to +/-40 V with selectable tips
•
Superior noise and rejection:
o
>100 dB common mode rejection ratio (CMRR)
o
Low loop inductance
o
Low attenuation
•
Gain accuracy of 2.5% typical, 4% guaranteed
•
ProBus interface with automatic scaling
•
Auto Zero capabilities
Method of Operation
The low-attenuation tip makes a three-wire (Signal, Reference, and Shield) electrical connection
to the device under test (DUT). The Signal connection wire is coaxial and attaches to the high
side of the signal measurement. The Reference wire and Shield wires are non-coaxial and attach
to the low side of the signal measurement. The Reference wire carries the signal return current,
while the Shield wire carries the current that is associated with the stray parasitic capacitances.
The output of the tip is input to the transmitter where an integrated, low-noise electrical amplifier
amplifies the attenuated signal, which is then frequency modulated in optical form for transmission
across the fiber optic cable. A subcarrier to the main modulation signal carries tip identifying
information so that attenuation and voltage scaling can be communicated to the oscilloscope.
The receiver demodulates the fiber optic signal to an electrical signal for input to the
oscilloscope. The subcarrier tip attenuation information is communicated through the
oscilloscope ProBus interface for proper voltage scaling.
