PDR302

EARTH RESISTANCE METER

取扱説明書
INSTRUCTION MANUALCONTENTS[1] Warning Instruction for safe use ………………………… 15[2] INTRODUCTION ……………………………………………… 16[3] PANEL ARRANGEMENT AND ACCESSORIES ………… 17[4] OPERATION …………………………………………………… 18
1. Arrangement of Auxiliary Earth Bars and Connections … 18
2. Measurement of Earth Resistance Using the Tripolar
System ……………………………………………………… 19
3. Measurement of Earth Resistance Using the Bipolar
System ……………………………………………………… 19
4. Measurement of Leakage Voltage Using the ACV ……… 20
5. Replacing the Batteries …………………………………… 20
6. Maintenance ………………………………………………… 21[5] SPECIFICATIONS …………………………………………… 22− 14 −

[1] Warning Instruction for safe use(80 %— 15—
1 −−

[2] INTRODUCTION

The Sanwa PDR302 Earth Resistance Meter is just the device tosatisfy these requirements as it features solid-state circuitry andautomatic direct reading of earth resistance using a batterypowered constant-current system. Some of the main beneﬁts andadvantages of the PDR302 include:

1.5 V

〜30 V

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[3] PANEL ARRANGEMENT AND ACCESSORIES⑲Black

⑭Blue

⑮Red

⑯⑰
⑱

12345
67

8
9Meter (indicator)
Pointer
Zero adjuster
Earth resistance scale(0〜10 Ω ), black
AC voltage scale(0〜30 V ), red
Range switch
Earth resistancemeasurement switch(push-button)
Power supply
indicator/battery checkE terminal (for grounding)

10
11
12
13
14
15
16
17
18
19

P(S) terminal (for auxiliary grounding)C(H) terminal (for auxiliary grounding)
Panel
Rear caseE-terminal connection cord (black),
approx. 5 m, with alligator clip (black)
P (S) terminal connection cord (blue),
approx. 10 m, with alligator clip (blue)
C (H) terminal connection cord (red),
approx. 20 m, with alligator clip (red)Lead wire reel, x 3
Earth bars (metal), 2 pcs.
Auxiliary grounding value excess
indicator lamp

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[4] OPERATION
1. Arrangement of Auxiliary Earth Bars and Connections

4.5 V

10 m

10 m

10 Ω
5〜10 ｍ5〜10 ｍ5ｍ

P C

WARNING

Take extra care not to drop the earth bars or pierce anythingwith them when carrying them or inserting them into theground. The tips of the earth bars are very sharp.
As shown in Figs.1 and 2, the auxiliary bars are arranged parallelto the earth (E) at intervals of 5〜10 meters. Where it is impossible
to align them parallel, a certain amount of bending ( E , P(S) C(H)≧ 120゜) is allowed.
When the nets are used instead of the bars, the RP(RS) andRC(RH)at the earth poles read larger. Normally, the impedance ofthe power supplying constant AC current to E-C(H) is high enoughto prevent reading errors due to a slight increase of resistance.
However, when the nets are used on a concrete surface, wet themto enable better contact with the ground. Measurement is notpossible on asphalt surfaces. Once the bars have properly set,make connections as illustrated.

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2. Measurement of Earth Resistance Using the Tripolar System
WARNING
Make sure that the object being measured — an electric appliance, forexample — is properly grounded. If the object is improperly grounded or
not grounded, commercial voltage may leak into or be applied to theobject. Double-check all safety precautions before starting measurement.

CAUTION:

Make sure the earth bars are inserted into the ground securely. If they are
improperly inserted, RP(RS) and RC(RH) values increase. This will result inerrors in measurement values and instabilities in indicated values.
1. The range switch is placed at one of the three ranges to be selectedaccording to the size of the earth resistance (RE).
2. Press the MEASURE PUSH switch. The power indicator lamp (ON) willlight red and the pointer will point at the earth resistance value (RE).
3. For the “X1” range, the ﬁgures along the arc are read directly (0〜10Ω). For the “X10” and “X100” ranges, they are read multiplied by 10 for
0〜100 Ω and by 100 for 0〜1000 Ω.
4. If the red LED (OVER AUX. R) on the upper left of the meter scale
lights after the MEASURE PUSH switch is pressed, this means theauxiliary grounding resistance value is excessive and correct
measurement cannot be performed. Should this happen, re-insert theearth bars into the ground.
5. If the power indicator lamp (ON) starts blinking after the MEASURE
PUSH switch is pressed, this means the batteries are low. Replacethem with new ones. For details, refer to “5. Replacing the Batteries.”

3. Measurement of Earth Resistance Using the Bipolar System
1. When earth is available whose resistance value has been alreadydetected or whose resistance is extremely low and can be regarded
as immaterial with respect to the earth resistance in question, you canmeasure unknown earth resistance by taking advantage of theelectrical circuit ground at hand.
2. The earth of unknown resistance is connected to the terminal E.
Next, insert the plugs of the C-terminal connection cord to the P (S) andC(H) terminals and connect the alligator clip to a point with known earth
resistance value.
3. The value measured with this method is the sum of an unknown
earth resistance RX and known earth resistance rE. If the value isalready known, obtain the true value by subtracting the known earth
resistance value rE from the meter reading RE.
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Earth resistance to be measured: Rx
Rx = RE – rE
Connect to a point with known earth resistance
ERxrE
PC (H) terminal connection cord (red)CMeter reading RE

Fig.3

4. Measurement of Leakage Voltage Using the ACVWARNINGS
1. Never attempt to supply voltage over 30 V — the maximum
allowable voltage — since the ACV of this unit uses leakage
AC voltage (ground voltage).
2. Never supply standard commercial voltage (AC 100 V forexample).
1. Once connections have been made, turn the range switch “ACV.”
2. The pointer responds if there is any earth voltage present to indicate
leakage AC current ﬂowing into the earth circuit. The red 0〜30 V
scale reads it.
3. If the scale reads above 5 V, there will be interference with earth
resistance measurement. In this case, before taking measurement,
open either the power circuit, the equipment using the earth, or its
earth circuit to reduce the effect of the voltage leak.
4. Earth voltage can be checked independently across E and P (S)without using the C(H) terminal.

5. Replacing the Batteries

1. When the batteries are low, the power indicator lamp (ON) starts
blinking after the MEASURE PUSH switch is pressed. When thishappens, replace the batteries with new ones. Refer to Fig.4 forreplacing the batteries.
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3 mm
42. Unfasten the screw from the battery compartment cover on theback of the unit. While pressing the rectangular protrusion in
the center of the cover as shown in Fig.4 Ⓐ , slide it down toremove it. Insert new batteries and align them according to thebattery directions shown in Fig.4 Ⓑ.
3. When the new batteries are loaded, replace the cover on thebattery compartment and tighten the screw to secure it.

CAUTIONS

1. Be sure to use speciﬁed batteries only. Never mix different
types or brands of batteries even if the rated voltage is thesame.
2. To avoid deterioration of performance, use only brand-new
batteries when replacing batteries.

6. Maintenance

1. Remove the batteries when not using the tester for extendedperiods.
2. Do not drop the instrument or otherwise subject it to severe
shock. Do not expose it to high temperatures or moisture.
3. The indicator cover is treated with anti-electriﬁcation coating. Do
not rub it hard with a dry cloth. If the coating is found ineffective,
you can spray it with disc cleaner as a temporary measure.

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[5] SPECIFICATIONS
1. Measurement Ranges
Ω(earth resistance):
X1 reading 0〜 10 Ω(0.2 Ω per scale)
X10 reading 0 〜 100 Ω(2 Ω per scale)
X100 reading 0 〜 1,000 Ω(20 Ω per scale)ACV (leakage voltage) 0 〜 30 V(1 V per scale)
2. Accuracy±5 % fs for Ω x 1±2.5 % fs for Ω x 10, Ω x 100±2.5 % fs for ACV
3. Batteries
R6(SUM-3)x6
4. Method of Measurement
Constant-current system (tripolar & bipolar)5. Constant Current AC Power
Abt. 100 V(1 kHz), through inverter
6. Auxiliary grounding value alarm LED lights at approx.10 kΩ or more
7. Battery Alarm
Blinking LED, approx. 6.5 V operation voltage(LED normally lights during measurement)
8. Accuracy Guarantee Temperature/Humidity Range
15 ℃〜35 ℃, 80 % RH or lessNo dew condensation allowed
9. Operating Temperature/Humidity Range
0 ℃〜40 ℃, 80 % RH or lessNo dew condensation allowed
10. Accessories
Measurement cords: 1 ea., black 5 m / blue 10 m / red 20 m] TL-66
3 lead wire spools
Alligator clips:
1 ea., black / blue / red (CL-302)
Earth bars:
2 ea. (CL-ER)
Carrying case:
1 (C-PDR302)
Storage bag:1 (C-302CB)
Instruction manual: 1
11. Dimension and Mass
175 x 118 x 55 mm, Abt. 500 g(main unit)− 22 −

本社=東京都千代田区外神田2−4−4･電波ビル
郵便番号=101-0021･電話=東京（03）3253−4871（代）大阪営業所=大阪市浪速区恵美須西2−7−2
郵便番号=556-0003･電話=大阪（06）6631−7361（代）SANWA ELECTRIC INSTRUMENT CO.,LTD.
Dempa Bldg,Sotokanda2-Chome Chiyoda-Ku,Tokyo,Japan

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