Prostat PRS-812 User manual

PRS-812
RESISTANCE METER
User Manual

PROSTAT® PRS812 RESITANCE METER
Secon Topic Page
I. Introducon & Descripon 4
II. Cauons & Warnings 7
III. Controls, Connecons & Indicators 9
IV. Baery Installaon and Replacement 15
V. Setup & Calibraon 16
VI. Instrument Operaon 18
VII. Instrument Maintenance 31
VIII. Warranty Informaon 32
General Specificaons 34
Instrument Controls 35
Table of Contents
Copyright © 2012 by Prostat® Corporaon. All rights reserved. Printed in the United States of America. No part of this
manual may be used or reproduced in any manner whatsoever without wrien permission. For informaon contact
Prostat Corporaon, 1072 Tower Lane, Bensenville, IL 60106 USA
Prostat is the registered trademark of Prostat® Corporaon

4Rev. C / January 2012
PRS-812 Resistance Meter
I. Introducon & Descripon
The PRS-812 Resistance Meter makes precision resistance measurements from
0.1 up to 1.0x1012 ohms with an overall measurement tolerance of ±5%. It is
capable of measuring up to 2.0x1014 ohms with tolerance depending on proce-
dures and condions. The PRS-812’s wide range and close tolerance make it the
ideal ESD Auding instrument for measuring resistance to a variety of ESD and
general industry specificaons. It is operated by programmed microprocessors
that control the instrument’s measurement process, resistance auto ranging,
test voltage selecon, electrificaon periods, and display funcons. It can be
operated in either fully automac or manual modes, or a combinaon of
automac and manual modes.
The PRS-812 is unique in that it records and stores up to 80 resistance measure-
ments in its own non-volale memory register. Stored data is summarized with
a push of a buon.
Its accuracy is based on its ability to rapidly make several measurements each
second, and average them unl a stable set of eight measurements, all within
5% tolerance, are obtained. The final averaged data is displayed as the resis-
tance measurement. Typically, measurements at less than 1 ohm are within
5% of tolerance, and those between 1.0 and 1.0x1012 ohms are within 0.5% of
laboratory references
While quite sophiscated in design, the PRS-812 Resistance Meter is easy to use and extremely helpful in
making accurate ESD auding measurements, or general resistance and connuity checks.
CAUTION
To avoid electrical shock or damage to the PRS-812 Resistance Meter, read
this manual completely before installing baeries or using the instrument.
A. Measurement Applicaons
The PRS-812 Resistance Meter is designed to measure resistance characteriscs of electrostac
discharge (ESD) control materials and products to current ESD industry standards, including:
Wrist Straps (ANSI/ESD S1.1)
Flooring (ANSI/ESD STM7.1)
ESD CP Grounds (ANSI/ESD S6.1)
Footwear (ANSI/ESD STM9.1)
Equipment (ESD SP10.1)
Material Handling Containers
Garments (ESD STM2.1)
Worksurfaces (ANSI/ESD S4.1)
Carts & Seang (ANSI/ESD STM 12.1)
Workstaons
Producon Aids & Hand Tools
Packaging (ANSI/ESD STM11.11, ANSI/ESD
STM11.12 & ASTM 257), and Other ANSI/
S20.20 ESD Program Control Elements
Note: Addional fixtures and electrodes supplied separately are required for many of these mea-
surement.
Figure 1: PRS-812 during
power up

5
Rev. C / January 2012
PRS-812 Resistance Meter
B. PRS-812 Resistance Meter Components:
The PRS-812 Resistance Meter includes the following items:
1. PRS-812 Resistance Meter Instrument with 2 each 9V alkaline baeries.
IMPORTANT NOTE
Only use alkaline baeries for opmal performance.
2. Two 10-foot leads (PRS-800LB & PRS-800LR) for general audit measurements up to 1.0x1012
ohms.
3. One heavy duty, black “Bulldog” clip (PRS-801BC)
4. Two Metal Alligator Clips (PSI-870MAC)
5. One Audit Test Bed (PTB-915)
6. One calibraon shunt for low range adjustment (PRS-801CC)
Oponal accessories are available for the PRS-812 Resistance Meter. Visit www.prostatcorp.com
for addional informaon.
C. PRS-812 Basic Descripon & Funcons
The PRS-812 Resistance Meter has several test, display and data logging funcons:
1. The PRS-812 six basic measurement modes are described in the following table

6Rev. C / January 2012
PRS-812 Resistance Meter
MODE DISPLAYED
UNITS
INDICA-
TION
RESIST.
RANGE
TEST
VOLTS
TEST
FUNCTIONS
AUTOMATIC 1
[Default]
1.0EXX
IND Ω- TΩAUTO AUTO. AUTO. AUTOMATIC RESISTANCE RANGE, TEST VOLTS, ELECTRIFICATION,
DISPLAY HOLD
SEE TABLE NOTE #1
AUTOMATIC 2 OHMS
Ω- TΩAUTO AUTO. AUTO.
MANUAL 1 1.0EXX
IND Ω- TΩMANUAL MAN
MAN. or
AUTO TEST ONLY; NO DISPLAY HOLD
UL= UNDER DECADE LEVEL
OL= OVER DECADE LEVEL
SEE TABLE NOTE #2
MANUAL 2 OHMS
Ω- TΩMANUAL MAN
MAN. or
AUTO
MANUAL/
AUTOMATIC 1
1.0EXX
IND Ω- TΩ
AUTO &
MANUAL
MAN. Start
AUTO
Run
AUTO.
MANUAL SETUP STARTING
DECADE, AUTO ADJUST RANGE,
TEST VOLTS, ELECTRIFICATION
DISPLAY HOLD
SEE TABLE NOTE #3
MANUAL/
AUTOMATIC 2
OHMS
Ω- TΩ
AUTO &
MANUAL
MAN. Start
AUTO
Run
AUTO.
TABLE NOTES:
#1 AUTOMATIC: RESISTANCE RANGES IN AUTO 0.1ΩTO <2.0E+12Ωas follows
@<10V: 0.1 TO <1.0E+04Ω(0.1Ω- < 10KΩ)
@ 10V: 1.0E+04 TO <1.0E+06Ω(10KΩ- < 1MΩ)
@100V: 1.0E+06 TO <2.0E+12Ω(1MΩ- <200TΩ) See Note Below
#2 MANUAL: RESISTANCE RANGES IN MAN 0.1ΩTO <2.0E+12Ωas follows
@<10V: 0.1 TO <1.0E+05Ω(0.1Ω- <100KΩ)
@ 10V: 1.0E+03 TO <1.0E+09Ω(1KΩ- <1GΩ)
@100V: 2.0E+05 TO <2.0E+12Ω(200KΩ- < 200TΩ) See Note Below
#3 AUTO-MANUAL: (Same as AUTOMATIC)
RESISTANCE RANGES IN AUTO-MANUAL 0.1ΩTO <2.0E+12Ωas follows
@<10V: 0.1 TO <1.0E+04Ω(0.1Ω- < 10KΩ)
@ 10V: 1.0E+04 TO <1.0E+06Ω(10KΩ- < 1MΩ)
@100V: 1.0E+06 TO <2.0E+12Ω(1MΩ- <200TΩ) See Note Below
2. The PRS-812 provides three separate test voltages for resistance measurements as indicated in
the table, above:
<10 Volts
10 Volts
100 Volts
In AUTOMATIC and AUTOMATIC/MANUAL modes the instrument automacally controls volt-
age and resistance range based on resistance characteriscs of materials being measured. In
the MANUAL mode the operator may select test voltage and and resistance range. Note that
the most efficient mode of operaon in AUTOMATIC/MANUAL for maximum baery life.

7
Rev. C / January 2012
PRS-812 Resistance Meter
3. The PRS-812 displays resistance Measurements in several ways:
a. 14 factory programmable LED’s each represenng one order of magnitude from <103to
>1012 ohms. LED’s have three colors, including:
GREEN
RED
YELLOW/ORANGE
NOTE
The PRS-812 provides very accurate measurements up to 1.0x1012 ohms, and
has the capability to display values up to 2.0x1014 ohms. However, the user
should be aware that accuracy degrades rapidly above 1.0x1012 ohms.
b. The large Liquid Crystal Display (LCD) includes an analog (1 - 10) scale and X1, X10 and X100
mulplier indicaon for measurement in Ω, KΩ, MΩ, GΩand TΩ.
c. Digital measurements are provided using integers and Ω, KΩ, MΩ, GΩ, TΩindicators, or in
exponenal format (1.0EXX) with Ω-TΩindicators.
4. The PRS-812 includes data logging (storage) capabilies for up to 80 data points when RECORD
is selected. The instrument will provide access to the memory register, calculate and display
Minimum, Maximum and Average of all measurements in the instrument’s memory whenever
RECALL is selected.
II. Cauons & Warnings
As with any electrical device, use proper safety precauons and safe measurement procedures to
avoid personnel shock and arc discharge.
A. The PRS-812 Resistance Meter is baery operated and delivers test voltages up to 100 volts.
IMPORTANT: Only use alkaline baeries in the PRS-812.
B. The instrument is current limited for safety, however, if improperly used it may be capable of deliv-
ering an annoying shock to a person touching conductors energized by the PRS-812, parcularly at
100 volts.
C. While current limited, a hazard exists in personnel reacon to a potenal shock.
D. To avoid personnel shock, follow the General Operaons instrucons at all mes. Do not touch
energized electrodes or fixtures when power is applied except as specifically described in this and
accessory instrucons.
E. Do not operate or store the instrument in damp environments or wet condions.

8Rev. C / January 2012
PRS-812 Resistance Meter
CAUTION
Storage or use of this instrument in high humidity, damp or wet condions
may cause damage to the instrument’s electronic circuits, effect performance
and can increase the possibility of personnel shock or arc discharge.
F. Do not use the PRS-812 in combusble or explosive environments
WARNING
Improper handling and use of energized circuits may cause arc discharge,
which in turn may cause the ignion of combusble materials or fumes.
Do not use exposed energized circuits in flammable areas.
G. Do not aempt to measure energized circuits with the PRS-812
H. Do not use the PRS-812 if it becomes damaged in any way
I. Only Prostat trained instrument personnel should aempt to service or repair the PRS-812
J. Other Safety & Operang Consideraons
1. This manual displays cauons and warnings alerng the user to hazardous operaon and ser-
vicing condions. CAUTION or WARNING headings throughout this publicaon flag this infor-
maon, where appropriate. Follow all cauon and warning instrucons at all mes.
2. The PRS-812 is a precision instrument and should be operated by experienced personnel famil-
iar with the use and handling of devices containing power supplies.
CAUTION
The PRS-812 Contains Electrostac Discharge Sensive (ESDS) components
and includes precision alignment of circuit elements. Only Prostat trained and
ESD Qualified instrument repair personnel should perform service.
3. The PRS-812 contains Electrostac Discharge Sensive (ESDS) components. Qualified personnel
should service it only at ESD Controlled workstaons. Do not aempt to dismantle the PRS-812

9
Rev. C / January 2012
PRS-812 Resistance Meter
without Prostat’s authorizaon and expert supervision. The instrument contains exceponally
clean circuits that are aligned and adjusted in a precise manner for opmal operaon and ac-
curate performance. Unauthorized opening of the PRS-812 housing will void the instrument’s
warranty.
WARNING
Unauthorized opening of the PRS-801 case or dismantling in any manner
WILL VOID THE INSTRUMENT’S WARRANTY.
4. Read this manual in its enrety before installing baeries or using the PRS-812.
5. Do not drop or cause unnecessary mechanical shock to your PRS-812 instrument.
6. Store the instrument in a clean, dry environment. Do not expose the instrument to wet, ex-
tremely hot or cold condions.
7. If the unit is stored in a cold environment, allow it to stabilize at room temperature before
powering up the unit. This will prevent damage due to condensaon that may accumulate on
the instrument’s circuit boards.
III. Controls, Connecons & Indicators
Before operang the PRS-812 instrument become familiar with each control and display funcon. A
thorough understanding of the instrument’s operaon will make its use a pleasant experience, en-
hance measurement accuracy, avoid mistakes and prolong the life of the instrument.
PRS-812 CONTROLS:
[1] FUNCTION/ MODE Toggles Through Six Operaon Modes
(1) AUTO: (AUTOMATIC) displays data in exponenal format 1.0EXX
NOTE: AUTO in exponenal format, e.g., 1.3E05, is the Default start up
mode when the instrument is turned ON.
(2) AUTO: (AUTOMATIC) displays data in Ω, KΩ, MΩ, GΩand TΩ. The instru
ment controls resistance ranges, test voltage and electrificaon periods in
AUTOMATIC mode.

10 Rev. C / January 2012
PRS-812 Resistance Meter
Figure 2: PRS-812 Controls & Display Indicators
(3) MANUAL: displays data in exponenal format 1.0EXX
(4) MANUAL: displays data in Ω, KΩ, MΩ, GΩand TΩ
InMANUAL, the operator selects resistance range in single decade
increments. Test voltage may be selected by the operator, or allowed
to funcon automacally based on resistance range selected. The
operator determines electrificaon period in seconds (SEC) using the
displayed mer in the center of the LCD.
(5) AUTO-MANUAL: displays data in exponenal format 1.0EXX
(6) AUTO-MANUAL: displays data in Ω, KΩ, MΩ, GΩand TΩ
In AUTO-MANUAL the operator may select the inial resistance range in
decade increments. Once set, the PRS-812 starts the measurement process
from the preset resistance decade, rather than re-zeroing itself for each
measurement. This feature saves measurement cycle me and extends
baery life. In this mode the instrument automacally controls test voltage,
range and measurement electrificaon period.

11
Rev. C / January 2012
PRS-812 Resistance Meter
[2] RESISTANCE RANGE
SELECTION Two Triangular Arrows Buons, UP (↑) and DOWN (↓), select Resistance
Measurement Range in single orders of magnitude while in MANUAL or
AUTOMATIC/MANUAL modes
[3] TEST VOLTS Manual Selecon of <10, 10 or 100 volts in MANUAL selects inial test
voltage. MANUAL Test Voltage & Resistance Limits are as follows:
@<10V: 0.1 to <1.0E+05Ω(0.1Ω- <100KΩ)
@ 10V: 1.0E+03 to <1.0E+09Ω(1KΩ- <1GΩ)
@100V: 2.0E+05 to <2.0E+14Ω(200KΩ- <200TΩ)
NOTE: Opmal minium measurement in MANUAL using 100
volts is 2.0E+05.
[4] RECORD/RECALL If REC is not displayed in the lower lecorner of the LCD, pressing RECORD/
RECALL once turns Memory Register ON [REC will then be displayed in
LCD]. If REC is ON and measurement data is stored in memory, pressing
RECORD/RECALL once will provide access to the memory register. Pressing
RECORD/RECALL successively will calculate and sequenally display
Minimum [MIN], Maximum [MAX] and Average [AVG] of data stored in the
Memory Register. If memory is ON and register contains stored data pressing
RECALL will provide the following informaon:
First Press RECALL: Provides access to data in Memory
NOTE: MEM XX Flashes in LCD indicang number of data points in the
register and the last measurement is displayed. Pressing DOWN (↓)and UP
(↑)displays other data points and their respecve posion in the register is
shown in the MEM XX secon of the LCD.
Second Press RECALL: Displays MIN Data Point in Memory
Third Press RECALL: Displays MAX Data Point in Memory
NOTE: When displayed, OL [Over Level] indicates a measurement greater
than (>) 2.0x1014 ohms, which is beyond the measurement capability of the
PRS-812.
Fourth Press RECALL: Displays AVG of all Memory Data Points
NOTE: OL [Over Level] measurements [>2.0x1014 ohms] are not included in
displayed average (AVG) calculaon.
Fih Press RECALL: Returns System to normal operaons
NOTE: If in RECALL mode, pressing RESET will return the instrument to normal
measurement operaons.

12 Rev. C / January 2012
PRS-812 Resistance Meter
NOTE
If RECALL is not pressed, a fih me OOPS will be displayed in the
LCD when TEST is next pressed. To Clear OOPS, press RESET. The instrument will
return to normal operaons.
[5] CLEAR In normal operaons CLEAR erases data in Memory Register, discards most
recent measurement, or turns the REC funcon OFF as follows:
a. When in any operaon mode, and HOLD is not displayed, pressing
CLEAR will erase all data stored in Memory.
NOTE
The process of turning the REC funcon OFF will clear the Memory
Register of all stored data. Be sure that this is indeed desirable before
pressing the CLEAR buon.
b. If a measurement is displayed in HOLD, prior to pressing RESET buton
pushing CLEAR will discard that held value and will not enter it into
Memory. Other data in Memory Register remains intact.
c. If reviewing data in the Memory Register while in the RECALL mode,
pressing CLEAR will discard the displayed data point. Other data in
Memory Register remains intact and indexes down one space to replace
the discarded data point.
d. When in any operaon mode, and HOLD is not displayed, pressing
CLEAR will erase all data stored in the Memory Register. Pressing OFF
will disble the REC mode and the instrument will be de-energized. When
powered up again the REC mode will remain disabled unl RECORD/RE-
CALL is pressed once.
[6] ON/OFF Turns instrument ON for normal operaons, performs funconal & Baery
tests, turns instrument OFF.
[7] BATT. TEST Displays GOOD on LCD if baery provides acceptable voltage for accurate
measurements, or displays Lo if unacceptable and baeries require replace
ment.
[8] RESET Saves measurement and prepares instrument for next test cycle, i.e., enters
measurement into Memory Register if REC is ON, and clears HOLD and the
LCD display between measurements.
[9] TEST Begins measurement sequence in accordance with selected mode
[10] BATTERY
BUSS CUT OFF Baery buss cut-offswitch is used to isolate the main baeries from the
instrument’s circuit during baery change, instrument storage and
transport.

13
Rev. C / January 2012
PRS-812 Resistance Meter
CAUTION
Switch baery buss to the OFF posion before changing baeries to avoid re-
verse polarity damage to the instrument.
LCD DISPLAY ELEMENTS
[11] Colored LED’s 14 LED’s across the top of the PRS-812 indicate measurement order of mag-
nitude in decades from <103to >1012 ohms.
NOTE
The PRS-812 provides very accurate measurements up to 1.0x1012 ohms, and
has the capability to “indicate” values up to 2.0x1014 ohms. However, the user
should be aware that accuracy degrades rapidly above 1.0x1012 ohms.
[12] PRS-812 Liquid Crystal Display (LCD) Elements:
AUTO When ON Indicates instrument in AUTOMATIC mode
MANUAL When ON indicates instrument in MANUAL mode
When AUTO and MANUAL are ON, indicates instrument is in
AUTO-MANUAL mode.
Analog Scale
& X100 Indicator The one decade analog scale elements darken to indicate measurement in
teger. X1, X10 or X100 darken to indicate the scale mulplier. Combine the
Analog indicators with Ω, KΩ, MΩ, GΩand TΩsymbols to obtain an analog
measurement.
MEM 00 Provides the number of data points stored in the Memory Register when
REC is ON and instrument is RESET in preparaon for a new measurement.
The Memory Register can store up to 80 data points.
Also idenfies a displayed data point’s posion in the Memory Register
when in the RECALL mode.
00 SEC Display’s electrificaon period required for the measurement when in TEST
during AUTOMATIC and AUTO-MANUAL measurement modes. In MANUAL,
provides connuous measurement ming up to 99 seconds, then restarts at
0 seconds.

14 Rev. C / January 2012
PRS-812 Resistance Meter
MIN Displayed when RECALL buon is pushed second me while in REC mode.
Number displayed when MIN is indicated is the Minimum data value in
Memory Register.
MAX Displayed when RECALL buon is pushed a third me (sequenally) in REC
mode. Number displayed when MAX is indicated is the Maximum data value
in Memory Register.
AVG Displayed when RECALL buon is pushed the fourth me (sequenally) in
REC mode. Number displayed when AVG is indicated is the Average of all
data values in Memory Register that are less than 2.0x1014 ohms. (OL’s are
not included in averaging calculaon.)
Note: Either the RECALL buon must be depressed a fih me or RESET
pressed to return the system to its operaonal, measurement mode.
REC Indicates that the Memory Register is ON and is Recording data each me
the RESET buon is depressed aer a TEST measurement.
ΩOhms: Indicates measurement between 0.1 and 999 ohms
KΩIndicates measurements from 1,000 (1.0x103) to 990,000 (9.9x105) ohms
MΩIndicates measurements from 1,000,000 (1.0x106) to 999,000,000 (9.9x108)
ohms
GΩIndicates measurements from 1,000,000,000 (1.0x109) to 999,000,000,000
(9.9x1010) ohms
TΩIndicates measurements from 1,000,000,000,000 (1.0x1012) to
200,000,000,000,000 (2.0x1014) ohms
<100 V Indicates <10, 10 or 100 volts being applied as the test voltage.
HOLD Indicates measurement is complete at the end of a TEST cycle. Holds data
point in display unl instrument is RESET or CLEAR is depressed.
Baery indicaon for low voltage
PRS-812 Connecons
[+] Posive
Terminal Power terminal for supplying Test Voltage to fixture or material under test.
[-] Negave
Terminal Sensing Terminal for measurement of current (I) through fixture or material
under test.

15
Rev. C / January 2012
PRS-812 Resistance Meter
Baery Compartment
Located in lower secon of case, opposite LCD display. Holds two 9V-transistor baeries. Two
screws secure the baery cover. Note: Use only Long Life Alkaline Baeries. Remove baeries
when instrument is not in use for long periods of me.
Figure 3: Opening Baery Compartment Figure 4: Install 2 each 9V Alkaine
Baeries
IV. Baery Installaon (See Figures 3 & 4)
For opmal baery life and avoid instrument damage, always replace the baeries with high energy,
alkaline baeries. Failure to do so will result in a diminished baery life, measurement error and potenal
instrument damage that could void the warranty.
The baery caps on the instruments you have purchased are designed to fit snugly. Please follow the di-
recons below for safe replacement of baeries.
A. Slide baery bus switch to the OFF posion (see figure 3).
B. Carefully remove the baery cover from the instrument.
C. Gently take the baeries from the baery compartment.
D. Unwind any baery lead that is wrapped around the top of the baery terminal. Do not pull bat-
tery connecon leads - this could cause instrument damage.
E. Very carefully place a flat head screwdriver between the baery terminals and gently lithe bat-
tery cover from the baery.
Baery Buss Switch
MUST be offduring
baery change.

16 Rev. C / January 2012
PRS-812 Resistance Meter
F. Properly dispose of any old baeries.
G. Posion the new alkaline baery under the baery cover.
H. With your thumb, press the terminals in place one at a me.
I. Carefully wind any excess baery lead around the baery terminal below the cap. To avoid instru-
ment damagae, do not pull baery connecon leads
J. Place the baeries back into posion with the baery terminal covers facing the lead spurce
within the baery case shown in figure 4.
K. Carefully posion the instrument baery cover back into place without force.
L. Replace the baery cover screws.
M. Slide baery buss switch to the ON posion.
Following the above direcons for baery replacement will insure that you do not damage the baery
covers or wires during this process.
NOTE
It is recommended to measure the voltage of each baery with a mulmeter. If the voltage of
one baery measures at or below 6.75 volts, replace that baery. If both baeries measure at
or below 6.75 volts, replace both baeries.
V. Setup & Calibraon
A. Seng up the PRS-812 for low resistance range calibraon
1. Posion Baery Buss Cut Offswitch to OFF posion
2. To install baeries, remove two Phillips locking screws and cover. Aach two Long-Life, Alkaline
9V baeries to the baery connecon terminals.
3. Posion baeries in compartment with power leads neatly posioned above baery connec-
ons. Carefully re-install baery cover and locking screws.
NOTE
Do Not change baeries with the baery buss ON. Always switch Baery Buss Cut Offto OFF
when changing baeries. Should the ON/OFF buon be depressed during baery change and
Baery Bus is ON the instrument may lock up and not funcon properly or be seriously dam-
aged. In this case, simply disconnect the baeries, then re-install with Baery Buss switch in
the OFF posion.
B. Low Resistance Range (<10 Ohms) Calibraon
1. Install the calibraon shunt (PRS-801CC) across the Negave (-) and Posive (+) Lead Terminals
(Figure 5, below).

17
Rev. C / January 2012
PRS-812 Resistance Meter
Figure 5: Low Resistance Range Calibraon Shunt Installaon
2. Press the Red ON/OFF power buon. The instrument display should become energized, each
LED will be tested in sequence, and GOOD will is displayed in the LCD if the baeries have
sufficient test capacity (figure 9).
Figure 6: Low Resistance Range Calibraon
using Reference Module
Figure 7: Start the Calibraon Sequence by
Pressing RESET then CLEAR within ½ Second
3. Allow the instrument circuits to warm-up for a few minutes; approximately 2 - 3 minutes are
sufficient, prior to compleng the calibraon sequence.
4. Press MODE once to shidisplay to ohms mode (Ω).
5. Press the Yellow RESET, then the Gray CLEAR buon within ½ second. The message CAL will be
displayed in the LCD. (See Figure 8)
6. Press the Yellow RESET buon to complete low range (0.1 to 10 ohm) calibraon. The CAL mes-
sage will automacally be cleared when RESET is pressed. (See Figure 8)
7. Press the Green TEST buon. Indicated resistance should be 1.02 (±0.02) ohms as shown in
Figure 8. Press RESET to clear the display. NOTE: If 1.02 (±0.02) ohms is not displayed, repeat
the calibraon process.

18 Rev. C / January 2012
PRS-812 Resistance Meter
8. Remove the calibraon shunt assembly from the lead terminals
9. The PRS-812 is now ready for wide range measurements from 0.1 to 1.0E+12 Ohms
Figure 8: Complete Calibraon Sequence by Pressing RESET. To confirm Calibraon,
Press TEST to measure the Calibraon Shunt resistance. Shunt resistance should display
1.02 Ohms ±0.02 Ohms
VI. Instrument Operaon
A. Overview of PRS-812 Operaon & Measurement Test Cycle Sequence
The following 10 points provide a general overview for calibrang and using the PRS-812 for resis-
tance measurements.
1. Slide Baery Buss Cut Offswitch to ON
2. Press Red ON/OFF buon once to power up PRS-812
a. Instrument performs circuit check, and tests LED’s, LCD display, and baery voltage.
b. LCD displays GOOD if baery voltage suitable for instrument operaon; displays Lo if bat-
teries require replacement
c. Instrument ends startup sequence in default AUTO, Exponent Display Mode 1.0EXX
3. Select Funcon Mode if other than AUTO, Exponent Display Mode 1.0EXX is desired by press-
ing MODE buon
4. Perform low resistance range calibraon aer 3 minute instrument warm-up, if desired
a. Install Calibraon Shunt between posive (+) and negave (-) terminals
b. Press RESET then CLEAR within ½ second

19
Rev. C / January 2012
PRS-812 Resistance Meter
c. CAL is displayed in LCD
d. Press RESET to calibrate instrument to shunt reference
e. Press TEST to measure shunt resistance of 1.02 ±0.02 ohms (Ω)
f. Press RESET buon to prepare instrument for the next measurement
g. Repeat calibraon procedure if necessary
h. Remove Calibraon Shunt
5. Carefully connect test leads to posive (+) [Power] and negave (-) [Sensing] terminals. Insert
right angle sleeved banana into instrument terminal, press gently while twisng into posion.
Standard 10-foot test leads are used for general audit measurements, and provides excellent
accuracy up to 1.0x1012 ohms
6. Connect test leads to electrodes, fixture or circuit to be measured
7. Press Green TEST buon to iniate Automac measurement Test Cycle
a. The resistance range is reset to minimum (0.1Ω). It is automacally adjusted in conjuncon
with the resistance characteriscs of the materials under test, based on:
(1) Test voltage; and,
(2) Current flow.
b. Test Voltage is reset to <10V and automacally increased in accordance with the following
material resistance characteriscs:
(1) <10 Volts: 0.1 to less than 1.0x104ohms (0.1Ω- <10KΩ)
(2) 10 Volts: 1.0x104to less than 1.0x106ohms (10KΩ- < 1MΩ)
(3) 100 Volts: 1.0x106to 2.0x1014 ohms (1MΩ- 200TΩ)
(4) When OL is displayed, it mean that the resistance is greater than 2.0x1014 ohms
c. Electrificaon period, i.e., the me period during which test voltage is applied to the ma-
terial under test, is automacally adjusted to the PRS-812’s measurement characteriscs
and industry standards (ANSI/ESD STM11.11). Typical electrificaon periods are:
(1) 2 to 3 Seconds: 0.1 to less than 1.0x104ohms (0.1Ω- <10KΩ)
(2) 2 to 4 Seconds: 1.0x104to less than 1.0x106ohms (10KΩ- < 1MΩ)
(3) 7 to 8 Seconds: 1.0x106to >1.0x1012 ohms (1MΩ->1TΩ)
(4) 15+ Seconds: 1.0x1012 to 2.0x1014 ohms (1TΩ- 200TΩ)

20 Rev. C / January 2012
PRS-812 Resistance Meter
8. When the PRS-812 displays and holds the final resistance measurement, HOLD is indicated in
the lower, right corner of the LCD.
The PRS-812 is processor controlled to obtain hundreds of measurements per second, and
to make rapid adjustments in resistance range and test voltage as necessary. It will display
the resistance measurement of the material under test based on the following criteria:
a. A digital numeric display is the averaged result of eight (8) individual, consecuve
measurements, each within ±5% of each other.
b. The display is connuously recalculated and updated during the measurement’s elec-
trificaon period.
c. The final displayed measurement is the averaged result of the last eight (8) individual,
consecuve measurements, each within ±5%, at the end of the electrificaon period.
d. If the material or test condions vary such that eight consecuve measurements, each
within ±5% of each other cannot be obtained, the PRS-812 will extend the electrifica-
on period unl the measurement criteria are met; or,
e. The electrificaon period will automacally be terminated and the most recent aver-
aged result of eight (8) individual, consecuve measurements will be displayed and
held. NOTE: Several material measurements that vary greater than 15 to 20 percent of
each other typically indicate inconsistencies in the material or test condions.
f. In rare cases, when a stable measurement cannot be obtained the display will reset.
NOTE:
NOTE: When several “held” measurements vary greater than 15 to 20 percent of each
other this typically indicates inconsistencies in the material or test condions.
9. To save the displayed measurement in the Memory Register and prepare the PRS-812 for the
next measurement, press the Yellow RESET buon. Pressing RESET causes three funcons:
a. Enters (saves) last measurement into Memory Register
NOTE
REC must be displayed in the lower, lecorner of the LCD in order to enter the
measurement in the Memory Register. If REC is not displayed, press RECORD/
RECALL once, then press RESET to save the data.
b. Increases LCD displayed number of data points in the Memory Register (MEM) by one, e.g.,
MEM 02
c. Returns the PRS-812 to its last funcon mode in preparaon for the next measurement
10. To make several measurements, simply press TEST to obtain the next measurement, and then
RESET to save it. Repeat the TEST and RESET process for each measurement.