ETS 220B User manual

Electro-Tech Systems –700 West Park Avenue, Perkasie, Pennsylvania 18944 D01654 Revision B –2020-10-01 –Page 1
High Impedance Voltmeter
ETS Model 220B Operating Manual
D01654

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Table of Contents
I. Important Safety Information
II. Description of contents
III. Setup Guide
IV. Quick Start Guide
V. Functionality
VI. Operation Details
VII. Maintenance/Calibration
VIII. Warranty
IX. Appendix A - Computer Interface
Revision History:
Revision A: Legacy version 2018
Revision B: Released 2020-11-05. Reformat, add new address.
Products described in this manual are designed and assembled in the U.S.A. by
Electro-Tech Systems, Inc.
700 West Park Avenue
Perkasie, PA 19844
www.electrotechsystems.com

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I. IMPORTANT SAFETY INFORMATION
SAFETY INSTRUCTIONS
The equipment described in this Manual is designed and manufactured to operate within defined
design limits. Any misuse may result in injury, electric shock, or discomfort to a person, incorrect
readings, or damage to the equipment. The following rules should be observed for installation, use
and maintenance. Read the following safety instructions before operating the instrument.
POWER
The unit may be operated as a battery powered device using two standard 9V rectangular batteries,
or as a plug-in AC device using the supplied 18V wall adaptor. The highly efficient circuit design
provides an operating life of about one (1) year under normal use for two 9 Volt alkaline batteries
OPERATION
DO NOT OPERATE WITH COVERS OR PANELS REMOVED. The unit handles input voltages as
high as 10,000 volts and all circuitry should be kept enclosed.
The metal enclosure of the unit must be connected to house ground or zero volts with respect to the
circuit being measured. If this is not done, the case of the meter may be at a dangerous potential
capable of causing injury or discomfort if touched.
The unit includes a high voltage probe and cable. The probe can become charged. Accidentally touching this
probe after measuring a high voltage can result in a mild shock. Probe tip is sharp –avoid a puncture wound.
The unit uses standard 9V batteries. Ensure that the batteries are inserted in the proper polarity. Keep any
spare batteries separated and the terminals covered, since shorting the 2 terminals to metal or to another
battery will result in damage or fire hazard.
DO NOT OPERATE WITH SUSPECTED EQUIPMENT FAILURES. If any odor or smoke becomes apparent
turn off the equipment and unplug it immediately. Failure to do so may result in electrical shock, fire or
permanent damage to the equipment. Contact the factory for further instructions.
DO NOT USE IN ANY MANNER NOT SPECIFIED OR APPROVED BY THE MANUFACTURER:
Unapproved use may result in damage to the equipment or present an electrical shock or fire
hazard.

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II. Description of Contents
Included:
Item
Qty.
Description
Model 220B
1
Circuitry in a metal enclosure with attached 42-inch probe cable
with red clip probe.
Ground Cable 1
1
A 42-inch black rubber cable featuring a black banana plug and an
alligator clip
Ground Cable 2
1
A 5’ black rubber cable featuring a green banana plug and a
alligator clip
Communication Cable
1
A 6-foot cable with DB9 female connectors on each end
Power Adapter
1
Wall-plug-in 18V power module., 100-260VAC input, 8.1W output
with attached cable and molded plug. ETS part # 0111-00001A

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III. Set-Up Guide
Step 1 –Unpack the unit
Verify all parts are present and have survived
shipping.
Step 2 Initial Setup
Connect the BLACK grounding cable to the
banana jack (GND) on the front panel.
If desired, the bail on the bottom of the
Voltmeter case may be flipped down to tilt the
Voltmeter upward toward the user, making it
easier to read.
Step 3 Power On
Insert two new 9V batteries in the battery
compartment, or connect the 18V wall
adapter. Push the POWER ON/OFF switch
to ON position (display on). The display
readout should be active. If the adapter is in
use, the display will be illuminated..
BATTERY USE CAUTION!
The POWER ON/OFF switch is the only
control on the unit. If using battery power,
always switch to the OFF position (display
off) when the Voltmeter is not in use to
ensure maximum battery life. Failure to turn
the unit OFF when not in use will result in
frequent battery replacement.

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Step 4 - Initial Status Check
A. If the BATT LO condition is on, replace
the batteries (2x9V) before making any
measurements. See the instructions in
Section VI of this manual.
B. Apply zero voltage input to the Voltmeter
by clipping ground cable to HV probe as
shown. Display should read 0 volts.
C. With 0 volts applied, if the voltage meter
does not read 0V, or if the OVER SCALE
condition is on, the Voltmeter is not
functioning properly and should be tested
and repaired before using it to make any HV
measurements.

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IV. Quick Start Guide
Step 1 –Turn on Power
Turn on Power, verify display is active.
Step 2 –Probe the Voltage
First connect the ALLIGATOR CLIP on the
grounding cable to a suitable ground (zero
voltage) point. Then hold the RED HIGH
VOLTAGE PROBE by its red plastic body
and place the pointed metal tip in contact
with the circuit to be measured.
Step 3 –Display
The digital readout will then display the
measured voltage directly in volts. A polarity
sign will appear to the left of the voltage
readout to indicate the polarity of the voltage.
Because of the extremely high input
impedance of the meter, allow a minimum of
5 seconds for the readout to stabilize after
the probe is in contact with the voltage point
being measured.

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V. Functionality
Introduction
In many instances, the accurate measurement of D.C. voltages in excess of 1,000 Volts, which
are produced by power supplies or voltage dividers with output (source) impedances in excess of
10 megohms, is required. In these situations, most readily available laboratory D.C. voltmeters
will be useless since they will have insufficient range and will “load” the source to such a great
extent that an accurate measurement is not possible.
Description
The Model 220B High Input Impedance Voltmeter, shown in Figure 1-1, is designed for accurate
and precise measurement of high voltage D.C. sources where minimal loading of the source is
required. The unit has a nominal input resistance of 70 Gigohms (70,000 Megohms) and is
capable of measuring D.C. voltages up to ±10,000 volts. Accuracy is better than ±1% full scale
and the direct reading, digital readout provides a resolution of 1 Volt.
Model 220B High Input Impedance Voltmeter
Measuring output from Model 812 High Voltage Power Supply
As a result of the unit’s very high input impedance and high accuracy, voltage sources as high as
±10,000 Volts with source impedances on the order of 100 Megohms can be measured with errors
of less than ±1% of full scale.
The unit is battery powered or an AC wall adaptor can be used to provide power. It is small and
lightweight making it ideally suited for both laboratory and portable field use. The highly efficient
circuit design utilizes two standard (user replaceable) 9 Volt alkaline batteries, which provide an
operating life of about one (1) year under normal use.

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The digital meter displays the measure voltage directly in ±volts. The digital meter also provides a
low battery indication to warn the user that the batteries should be changed. An over-scale
indication warns the user that the input range of the unit has been exceeded. The circuits within
the Model 220B are protected against over-scale inputs and external transients.
The unit is supplied with a high voltage probe assembly consisting of a 6” (152mm) long (red) H.V.
probe on a 42” (1m) H.V. cable with a 42” (1m) grounding cable. The H.V. cable is connected
directly to the unit via a pass-through on the front panel of the Voltmeter. The grounding cable
plugs into the banana jack on the front panel.
SPECIFICATIONS
Electrical
Voltage Range: 0 to ±10,000 volts D.C.
Absolute Maximum input: ±11,000 V
Input Resistance: 70 GigOhms ± 10%
Input Capacitance 150 pF + 10%
Accuracy: ±1.0% of full scale (max) at 25º C.
Resolution: 1 Volt
Settling Time: 5 seconds (max) to within ±0.5% of final reading.
Overscale Threshold: 10,500 V 5%
Power source: Two 9Volt alkaline batteries, or
AC Wall adapter (included) providing 18VDC,
Mechanical
Size: 7½” wide, 10” deep, 3” high
Weight: 2 lbs. (nominal)
Probe Cable Length: 42”
Environmental
Operating Temperature Range: 0 to 50 degrees C
Temperature coefficient: ±200 ppm/deg C (max)
Humidity: 0 to 70% RH (non-condensing)

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VI. Operation of the Model 220B
Display Details
The meter contains a dot-matrix display
readout that functions when power is on.
When the high voltage input to the Voltmeter is
within the nominal range of ±10,000VDC, the
display will indicate the value of the voltage
being measured directly in volts. The sign to
the left of the number is the polarity of the input
voltage. When the input to the Voltmeter is
zero, the DVM should read 0 ± 1V. The system
is auto-zeroing hence, no external zero
adjustment is provided nor is one required.
Backlit illumination of the display is
provided when the unit is operating on
AC power.
Over-Voltage Indication
When the input to the meter exceeds
±10,500VDC (±5%) the DVM will indicate this
over-scale condition by displaying a warning
message. When the input to the Voltmeter is
reduced to within the normal measurement
range (i.e., below ±10,500VDC), the readout
will automatically return to normal.
Battery Low Indication
The meter will warn the end user when either of
the Voltmeter’s two batteries reaches the end
of its normal life. When a Battery Low condition
is indicated, BOTH 9-VOLT BATTERIES
SHOULD BE REPLACED AS A SET. The
efficient design of the system should provide a
battery life of at least one (1) year under normal
use. This assumes that the Voltmeter is turned
on only when measurements are being made,
and not left on for long periods when not in use.

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Battery Replacement
To replace the unit’s 9-Volt batteries,
disconnect the high voltage probe from any
voltage source being measured and turn off the
power switch on the Meter’s front panel. On the
rear panel is a 2-drawer battery compartment.
Lift up each drawer and pull out. Remove the
old batteries and insert the new ones. Be
careful to observe the polarity. REPLACE
BOTH BATTERIES AS A SET with new 9-Volt
cells. Alkaline or non-alkaline batteries may be
used. Normal use may now be resumed.
Measurement technique
When making high voltage measurements of
sources with very high output impedances, the
user should hold only the RED PLASTIC BODY
of the voltage probe. Depending on the nature
of the voltage source being measured, if the
user touches a ground point, the meter case, or
other parts of the probe assembly (cable, BNC
connector, etc.) while a measurement is being
made, the accuracy of the measurement may
be affected.
GROUNDING
The black ground clip on the grounding cable is
connected directly to the metal case of the
voltmeter. This ground clip, or the ground lug
on the rear of the meter case, should always be
connected to house ground or zero volts
relative to the voltage being measured. If this
is not done, the case of the meter may be at
a high (potentially dangerous) voltage level,
and injury to personnel may result if the
case is touched.

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Alternate Grounding Method
If it is not possible (or not desirable) to use
the ALLIGATOR CLIP on the grounding
cable, the GND connection on the rear
panel of the Voltmeter housing may be
used to connect the Voltmeter to system
ground (zero potential). Any suitable
grounding wire may be used or the
included GREEN CABLE.
Over-Voltage Condition
If the high voltage input to the Voltmeter
exceeds approximately ±10,500V, the meter
will automatically switch to the OVER SCALE
mode and warn the user that the input range
has been exceeded. The input circuits to the
meter are over-voltage protected, however,
inputs in excess of ±10,500V must be avoided.
Input Protection
The Voltmeter circuits have been designed to
be resistant to both external high voltage
events and over-voltages. The High Voltage
Probe assembly is designed to allow
measurements to be safely made up to
±10,500VDC. The components and materials in
the probe are designed to operate up to
±10,500VDC, hence, ±10,500VDC IS THE
ABSOLUTE MAXIMUM RATING FOR THE
SYSTEM. Voltages in excess of this maximum
limit may permanently damage the unit. This
damage is not covered by the manufacturer’s
warranty.

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VII. Maintenance and Calibration
Calibration
For consistency of performance Annual manufacturer conducted calibration is required.
As with any test instrument, normal component aging and drift will require that the system be
tested and calibrated by a qualified test and calibration facility on a periodic basis to insure
that the unit is performing within its specification limits. It is recommended that the system be
fully tested and calibrated on an annual basis (once each year). If it is used in a harsh
environment where the instrument is exposed to wide temperature or humidity extremes or
is subjected to shock and vibration, a more frequent test and calibration schedule may be
indicated.
Because of the unit’s extremely high input impedance, tight performance specifications, and
the specialized nature of the test equipment required for proper test and calibration, only a
qualified facility should be used for this purpose. The following information is provided to aid
in testing and calibrating the unit, but must be performed with the proper equipment and by
qualified personnel.
Calibration addresses the following parameters:
1. Input Offset. With the grounding clip attached to the probe tip, the unit should read 0.0V.
2. Scale. Accuracy is checked at ±500V, ±1,000, ±2,000, ±4,000, ±6,000, ±8,000 and
±10,000 V
3. Over-Voltage detection threshold ±10,500 V
This unit contains active (semiconductor) devices that are static sensitive. When testing,
repairing, or calibrating this unit, proper precautions must be taken to insure that these
sensitive circuits are not damaged by improperly grounded personnel, soldering irons, or test
equipment.
To return equipment to ETS for calibration or repair it is first necessary to obtain a RMA
number, please call 215-887-2196 or email [email protected]

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VIII. Warranty
Electro-Tech Systems, Inc. warrants its equipment, accessories and parts of its manufacture to be
and remain free from defects in material and workmanship for a period of one (1) year from date of
invoice and will, at the discretion of Seller, either replace or repair without charge, F.O.B. Perkasie,
Pennsylvania, similar equipment or similar part to replace any equipment or part of its manufacture
which, within the above stated time, is proved to have been defective at the time it was sold. All
equipment claimed defective must be returned properly identified to the Seller (or presented to one of
its agents for inspection). This warranty only applies to equipment operated in accordance with
Seller’s operating instructions.
Seller’s warranty with respect to those parts of the equipment that are purchased from other
manufacturers shall be subject only to that manufacturer’s warranty.
The Seller’s liability hereunder is expressly limited to repairing or replacing any parts of the equipment
manufactured by the manufacturer and found to have been defective. The Seller shall not be liable for
damage resulting or claimed to result from any cause whatsoever.
The warranty becomes null and void should the equipment, or any part thereof, be abused or
modified by the customer or if used in any application other than that for which it was intended. This
warranty to replace or repair is the only warranty, either expressed or implied or provided by law, and
is in lieu of all other warranties and the Seller denies any other promise, guarantee, or warranty with
respect to the equipment or accessories and, in particular, as to its or their suitability for the purposes
of the buyer or its or their performance, either quantitatively or qualitatively or as to the products
which it may produce and the buyer is expected to expressly waive rights to any warranty other than
that stated herein.
ETS must be notified before any equipment is returned for repair. ETS will issue an RMA (Return
Material Authorization) number for return of equipment.
Equipment should be shipped prepaid and insured in the original packaging. If the original packaging
is not available, the equipment must be packed in a sufficiently large box (or boxes if applicable) of
double wall construction with substantial packing around all sides. The RMA number, description of
the problem along with the contact name and telephone number must be included in formal
paperwork and enclosed with the instrument. Round trip freight and related charges are the owner’s
responsibility.

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Appendix A. Computer Interface
The Model 220B has a 9-Pin sub min-D RS232A COMM PORT (Note 1) that provides real time data through
serial communication. A PC will receive data by simply sending character R (for result) to the device. A simple
program must be written by the user in order to collect data. The data can then be transferred to a spreadsheet
or other program to obtain the desired data logging and/or analysis. To utilize this function connect a standard
9 Pin sub min-D null modem cable to the serial port of the PC. The cable is the standard 3-wire null modem
connection (2 to 3, 3 to 2 and 5 to 5).
To collect data without writing a program, standard Hyper Terminal from any windows operating system can be
used. In most computers, to bring up the Hyper Terminal program click on “Start” (lower left hand corner),
select Accessories then Communications then Hyper Terminal. Under “Connect using” (on some older
Terminals it is the “Phone number”) select the correct COMM port, which the supplied cable is connected to.
Set the following properties:
Baud rate: 9600
Data bit: 8
Stop bit: 1
Parity: None
Flow Control: None
For the computer to receive the data, depress “R” to send the command signal to the ETS220B. The ETS
220B sends what is on the liquid crystal display. If the LCD displays OVERSCALE or Low Battery, the unit will
send the same message. The actual result will be sent as on the LCD displays to the host computer.
Note 1: Use ETS provided Null Modem cable to be sure of proper connections.