The Trek Model 156A Charged-Plate Monitor System is designed to provide quantitative measurements of the effectiveness of air ionization systems, as to audit ionizer performance.
The Model 156A employs a revolutionary charged-plate monitor design that utilizes an ultrahigh-impedance, high-voltage follower to monitor the ion collecting plate voltage. This technique provides very high accuracy and virtually infinite impedance loading of the plate, while allowing the ion collecting plate to be charged and monitored through the same small-diameter connection. This technique also makes the measurement capacitance independent of the physical size and shape of the ion plate. Therefore, the size and shape of an ion collecting plate, as well as the measurement capacitance, may be customer specified to match a particular ESD-sensitive device within a manufacturing process, or it may be made to conform to the EOS/ESD Association Standard STM3.1-2000.
The Model 156A features two modes of operation, a decay mode with easy-to-program start and stop voltages, and a float mode. For decay mode operation, the ion collecting plate is precharged to a level above the programmed START voltage. The time required to discharge the ion collecting plate from the programmed START voltage to the programmed STOP voltage due to incident ion flow to the ion collecting plate from the measured ion field is indicated by the Model 156A. In the float mode of operation, the plate is initially discharged to zero and then allowed to float to the voltage level dictated by incident ion flow to the ion collecting plate from the measured ion field.
The simplicity of the design of the Model 156A makes it very reliable and completely portable. The Model 156A is powered by an internal rechargeable battery that offers 8 hours of operation from a full charge.
The Trek Model 156A/1 has a serial interface port to connect with a computer. Computer Software allows the operator to program test sequences, save, or retrieve test results. Any series of tests can be duplicated, analyzed, programmed or retrieved using PC based software.
PERFORMANCE
Monitored Voltage Range0 to ±1100 V DC or peak AC.
Small Signal Bandwidth (-3 dB)DC to 1 kHz (measured at 20 V p-p).
Large Signal BandwidthDC to 10 Hz (measured at 2000 V p-p).
Zero Stability (referred to plate voltage)Drift with Time (no incident ion flow)Less than 6 V/minute.
Drift with TemperatureLess than 10 mV/°C, noncumulative.
Decay Mode Thresholds
Start Voltage156A unit,156A/1 unit and software programmable from 1 to ±1000 V in 1 V increments.
Start Accuracy156A unit,156A/1 unit and software within ±1 V of programmed start voltage.
Stop Voltage156A unit,156A/1 unit and software software programmable from 0 to ±999 V in 1 V increments.
Stop Accuracy156A unit,156A/1 unit and software within ±1 V of programmed stop voltage.
Plate Self-Discharge (unpolarized)Less than 12 V/minute.