Model 341B High-Sensitivity, DC Stable ESVM

Replaces 341A

The Trek Model 341B is a DC stable, high-voltage precision electrostatic voltmeter for making noncontacting surface voltage measurements in the range of 0 to ±20 kV DC or peak AC. Research and industrial applications include charge accumulation monitoring of the LCD production processes, monitoring surface potentials in the electrostatic painting process, research and development in the electrophotographic process, and measuring electrostatic potentials on polymers, rubber, fabrics, and paper.

The Model 341B voltmeter employs a field-nulling technique for noncontacting voltage measurement that achieves DC stability and high accuracy even if the probe-to-surface spacing changes. This permits measurements of either stationary or moving surfaces without the need to establish fixed spacing to maintain accuracy.

The Model 341B patented probe design eliminates the need for close tolerance components. This significantly improves noise and drift performance, both in the presence of contaminating particulates and under conditions of high humidity and wide temperature ranges.

A precision voltage monitor provides a low-voltage replica of the measured electrostatic potential for monitoring purposes, or for use as a feedback signal in a closed-loop system. The Model 3450 probe assembly includes the sensitive electrode and preamplifier. A three (3) meter cable permits remote probe positioning.

The Model 341B can be operated on a bench top or, with optional hardware, in a standard 19-inch rack.

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PERFORMANCE

• Measurement Range
  0 to ±20 kV DC or peak AC.

  Accuracy
  Better than ±0.1% of full scale
  as referred to the voltage monitor).
  

  Speed of Response 
  (10% to 90%) 
  Less than 200 µs for a 1 kV step change.
  Less than 5 ms for a 20 kV step change. 

  Full Signal Bandwidth 
  DC to better than 25 Hz.

  Stability
  Drift with Time
  Less than 100 ppm/hour, noncumulative.
  Drift with Temperature
  Less than 200 ppm/°C.

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PRODUCT FEATURES

• High-Voltage Ready LED
  A LED indicator illuminates when the Model 341B electrostatic voltmeter is ready to make high-voltage measurements.

  High-Voltage ON/OFF
  A two-position toggle switch that turns on and off the high voltage supply inside the instrument.  This switch will only function when the High-Voltage Ready LED is illuminated.

  Zero Adjust
  A ten-turn control to null offsets or other zero errors which occur within the system.

  Voltage Monitor Output
  A buffered output providing a replica of the measured voltage.
  Scale 
  1/1000th of the measured voltage.
  Output Noise
  Less than 20 mV rms (measured using the true rms feature of the Hewlett Packard Model 34401A digital multimeter).
  Output Impedance
  Less than 0.1 ohm.

  Voltage Display
  4 1/2 digit LED display.
  Range
  0 to ±19999 V.
  Resolution
  1 V.
  Zero Offset
  Less than ±2 counts, referred to the voltage monitor.
  Sampling Rate
  Three (3) readings per second.

  Power On/Off 
  A two-position rocker switch that turns on and off the main power.

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PROBE

Probe holder assembly (not supplied) should be of a non-dissipative material with insulating properties of more than 
10 10 ohms and be able to withstand voltages of more 
than ±25 kV. 

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

Standard Resolution Probe
Model 3450 (side viewing).
Aperture Size 
3.05 mm x 1.52 mm.

High Temperature Probes 
(up to 100 °C)
Model 3455ET (end-viewing).
Aperture Size 
1.52 mm diameter.
Model 3453ST (side-viewing).
Aperture Size 
3.05 mm x 1.52 mm.

Probe Body Type
Square. 

Dimensions 
11.8 mm H x 11.1 mm W x 76 mm L
(0.5" H x 0.4" W x 3" L).

Probe Cable Length
3048 mm ±76 mm (10 ft. ±3 in.).

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ACCESSORIES

• Accessories Supplied
  • Operator’s manual and line cord.
• Optional
  • Model 3450EC Probe Extension Cable 
    (from Model 341B to Probe) (p/n17218) 
    
    Model 3460-1 Line Driver (p/n 17181)
    
    Full-Rack Mounting Kit 612RA Rack Mount Kit (19-inch) (p/n C4085)

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GENERAL

• Power Requirements
  Line Supply 
  Factory set for one of two ranges:
  90 to 127 V AC or 180 to 250 V AC, at 48 to 63 Hz
  (specify when ordering). 

  Operating Conditions
  Temperature
  0°C to 40°C.
  Relative Humidity
  To 90%, noncondensing.

  Dimensions
  230 mm H x 441 mm W x 432 mm L
  (9.06" H x 17.36"  W x 17" L).

  Weight
  17 kg (37 lb).

  Voltage Monitor Connector
  BNC coaxial connector.

  Ground Receptacle
  Binding post.

  AC Line Cord Receptacle
  Standard three-prong line cord receptacle with an integral fuse holder.

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CERTIFICATION

TREK, INC. certifies that each Model 341B is tested and calibrated to specifications using measurement equipment traceable to the National Institute of Standards and Technology or traceable to consensus standards. A Certificate of Calibration accompanies each instrument when it is shipped from the factory.

Low-Voltage Safety Compliance 
(EN 61010-1)
Overvoltage Category
CAT II: Local-level mains, appliances, portable equipment.
Pollution Category
Degree 1: Operate in environments where no pollution or only dry, nonconductive pollution occurs.

Copyright © 2004 TREK, INC.  All specifications are subject to change.

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