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.