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Products > ESD > Electrostatic Detectors & Sensors

Model 875 Electrostatic VoltAGE SENSOR

Trek’s new Electrostatic Voltage Sensor, Model 875, is designed for in-line monitoring of electrostatic charge build-up, which if left unchecked would disrupt manufacturing processes and/or cause product degradation and early life failure of semiconductors and other charge-sensitive components. Used to monitor static charge levels within manufacturing equipment such as conveyors, handlers, and other tools.

Trek’s Model 875 features an automatic calibration technique to maintain high accuracy and speed over wide variations of the spacing between the non-contacting measurement probe and the surface under test.

Other features include a voltage measurement range of ± 500 V DC or peak AC, accuracy of ±0.5%, speed of 25 ms, and low noise of 1% rms of full scale. Buffered output voltage and current monitors (4 to 20mA) are provided for remote monitoring and alarm purposes.

The unit is powered by +24 V DC and is housed in a standard DIN package to enable standardized mounting.


Show/Hide Product Technical Information


At 4 mm ±1 mm probe-to-surface distance

Measurement Range
0 to ±500 V DC or peak AC.

Measurement Accuracy
At the Voltage Monitor Output
Better than ±0.5% of F.S.
At the Current Monitor Output
Better than ±3% of F.S.

Current Monitor (4-20 mA)
Linearly related to the measured input voltage.
Scale Factor (+4 mA to +20 mA representing a -500 V to +500 V):
-500 V = 4 mA, 0 V = 12 mA, +500 V = 20 mA.

Speed of Response (10% to 90%)
Less than 25 ms for a 0 to ±500 V step change.


Probe Dimensions
5.6 mm square x 50 mm L

Aperture Orientation / Body Type
Side / Square.

Probe Cable Length
3.0 ±0.1 meters.

Recommended Probe-to-Surface Separation
4 mm ±1 mm.

An optional probe holder fixture is available - contact factory.



Voltage Monitor Output
A low voltage output which is linearly related to the
measured voltage value.
Scale Factor
(monitor output to measured value)
1 V/50 V.
Less than 1% rms of full scale (F.S.)
Output Load Current
5 mA, maximum.
Output Impedance
Less than 100 Ω.

Current Monitor Output (4-20 mA)
An output current which is linearly related to the
measured voltage. The voltage compliance range is +16 V.
Scale Factor
+4 mA to + 20 mA representing a -500 V to +500 V:
-500 V = 4 mA,
0 V = 12 mA,
+500 V = 20 mA.

Digital Enable
An external control TTL signal.
A TTL HIGH (or open) will disable
all internal power supplies.
A TTL LOW will provide normal
ESVM operation.

Fault Warning Output
A TTL output signal. A TTL HIGH
indicates normal operation of the
Model 875. A TTL LOW indicates
a fault condition such as: out of
range operation (circuit is
measuring a voltage greater than
±500 Volts), failure of the probe,
or circuit malfunction.

ZERO Adjustment
A potentiometer adjusts for zero volts at the voltage
monitor output when the probe is measuring a zero
volt source.

Power ON Indicator
A LED indicator illuminates when power is applied to
the unit.


An optional probe holder fixture is available - contact factory for additional information.


Power Supply Voltage
+24 V DC ±10%.
Power Supply Current
150 mA, maximum.

Power ON Indicator
A LED indicator illuminates when
power is applied to the unit.


TREK, INC. certifies that each Model 875 is tested and calibrated to specifications using measurement equipment traceable to the National Institute of Standards and Technology or traceable to consensus standards.

Caution: These instruments are designed to make electrostatic voltage measurements only. Do not use these instruments to make measurements of “hard” voltage sources or voltage sources which can deliver currents high enough to cause harmful shocks or personal injury.

All specifications are subject to change.