Hioki 3181-01 Instruction Manual

INSTRUCTION MANUAL

3181-01

DIGITAL POWER HiTESTER

Contents

Introduction i
Inspection i
Safety Notes ii
Notes on Use iii

Chapter 1 Introduction 1

1.1 Features 2

Chapter 2 Specifications 3
Chapter 3 Principle of Operation 5

3.1 Power Measurement 5

3.2 Current and Voltage Measurement 7

3.3 Integrated Watt Value 8

3.4 Crest Factor 10

Chapter 4 Names and Functions of Parts 11
Chapter 5 Operation 19

5.1 Preparing for Measurement 19

5.2 Power, Current and Voltage Measurement 22

5.3 Integrated Watt Value Measurement 23

Chapter 6 Applications 27

6.1 Determing the Power Factor 27

6.2 Connecting the Recorder 27

6.3 Printer Connection 28

6.4 External Control Terminal 30

6.5 Data Output Connector 31

6.6 Inputs Exceeding the Measurement Range 34

6.7 Three-Phase Three-Wire Connection 35

Chapter 7 Maintenance and Service 37

7.1 Battery Replacement 37

7.2 Fuse Replacement 39

7.3 Cleaning 40

7.4 Service 40

―――――――――――――――――――――――――――――――――――――――

I

I

ntroduction

Thank you for purchasing this HIOKI "3181-01 DIGITAL
POWER HiTESTER ." To get the maximum performance
from the unit, please read this manual first, and keep
this at hand.

nspection

When the unit is delivered, check and make sure that it
has not been damaged in transit. If the unit is damaged,
or fails to operate according to the specifications, contact
your dealer or HIOKI representative.

Accessory

Instruction Manual 1
Power cord 1

i

―――――――――――――――――――――――――――――――――――

Inspection

ii

R

G

N

S

―――――――――――――――――――――――――――――――――――――――

afety Notes

This Instruction Manual provides information and
warnings essential for operating this equipment in a safe
manner and for maintaining it in safe operating
condition. Before using this equipment, be sure to
carefully read the following safety notes.

Safety symbols

In the manual, this mark indicates explanations
which it is particularly important that the user read
before using the equipment.

The following symbols are used in this Instruction
Manual to indicate the relative importance of cautions
and warnings.

Indicates that incorrect operation presents extreme

DANGE

danger of accident resulting in death or serious
injury to the user.

Indicates that incorrect operation presents

WARNIN

significant danger of accident resulting in death or
serious injury to the user.

Indicates that incorrect operation presents

CAUTIO

possibility of injury to the user or damage to the
equipment.

NOTE

Denotes items of advice related to performance of
the equipment or to its correct operation.

―――――――――――――――――――――――――――――――――――

Safety Notes

―――――――――――――――――――――――――――――――――――――――

R

G

.

N

iii

otes on Use

In order to ensure safe operation and to obtain maximum
performance from the unit, observe the cautions listed
below.

DANGE

WARNIN

Always connect the voltage cable to the secondary
side of a breaker. On the secondary side of a
breaker, even if the lines are shorted the breaker
can trip and prevent an accident. On the primary
side, however, the current capacity may be large,
and in the event of a short-circuit there may be a
serious accident.
This unit cannot be used on voltage lines of 250
Vrms. If the voltage exceeds 250 VAC, there will be
a short-circuit accident or electrocution accident
will result.

In order to prevent an electrical accident, do not
make any connections while the power supply or
the device to be measured is on. Turn off the
power for both devices before proceeding.
The power supply voltage for this unit is switchable
To avoid electrical accidents, check that the voltage
selector is set correctly for the supply voltage you
are using.
In order to maintain safety and assure the stable
operating performance of this unit, be sure to
connect the ground terminal to a proper ground.

―――――――――――――――――――――――――――――――――――

Notes on Use

iv

N

―――――――――――――――――――――――――――――――――――――――

CAUTIO

NOTE

･ Before measurement, check the position of the range

switch. The unit may be damaged if current or voltage
exceeds the measurement limit is applied for a long
time.

･ Before using the unit, make sure that the sheathing on

the leads is not damaged and that no bare wire is
exposed. If there is damage, replace it with a new one.

･ Do not store or use the unit where it will be exposed to

direct sunlight, high temperatures, high humidity, or
condensation. If exposed to such conditions, the unit
may be damaged, the insulation may deteriorate, and
the unit may no longer satisfy its specifications.

･ To avoid damage to the unit, do not short the output

terminal and do not input voltage to the output terminal.

･ After initiating watthour measurement by pressing the

start button, do not alter the settings of the range switch,
the time setting dial or the time unit switch.

･ The 3181-01 is not certified for commercial metering.
･ The 3181-01 uses a voltage transformer (PT) and current

transformer (CT), which do not transmit DC. It is
therefore not possible to measure a signal (for example
full-wave or half-wave rectified) which includes a DC
component.

･ Do not use the 3181-01 to measure equipment with

ratings outside its ranges or whose current consumption
continuously exceeds 15A.

―――――――――――――――――――――――――――――――――――

Notes on Use

1

1

n

―――――――――――――――――――――――――――――――――――――――

Chapter

Introductio

The 3181-01 is a compact, multifunction power meter
providing power, current, voltage and watthour
measurements on equipment such as consumer products.
Current and voltage are indicated as true rms values,
enabling accurate measurements even on distorted
waveforms.

The integrator contains a timer allowing integration time
to be set in ranges 1 to 99 minutes or 1 to 99 hours. With
several output terminals, the 3181-01 can be linked to a
data recorder or a printer, enabling easy recording of
measurement data.

―――――――――――――――――――――――――――――――――――

Chapter 1 Introduction

2

1

―――――――――――――――――――――――――――――――――――――――

.1 Features

(1) Power, current, voltage and watthour measurements in a

single unit

(2) True rms reading of voltage and current values

unaffected by distorted waveforms

(3) Integrator timer can be set in ranges 1 to 99 minutes or 1

to 99 hours. (set timer at 00 for continuous integration)

(4) Auto-zero circuit ensures accurate power and watthour

measurements over long time spans.

(5) Three simultaneous outputs for power, current and

voltage

(6) Connecting the optional 3171 DIGITAL PRINTER to the

data output connector makes it possible to record power
consumption and average power values over time.

(7) Watthour data is protected against power failures by a

battery backup function.

(8) Compact, lightweight and highly portable

―――――――――――――――――――――――――――――――――――

Chapter 1 Introduction

3

,

)

2
s

―――――――――――――――――――――――――――――――――――――――

Chapter

Specification

Display (Power meter) 1999 digit LCD

(Integrator) 999999 digit LCD

Sampling rate (Power meter) Approx. 3 samples/s
Measurement

functions

Timer setting ranges (Integrator) 1 to 99 min/1 to 99 h
Timer accuracy (Integrator) ±0.01 %±1 s (at 0℃ to 40℃)
Measurement range (Power meter) Power: 200/2000 W

Accuracy (Ambient
temperature: 23℃±5℃
line power: 50/60 Hz,
power factor: 1.0)

Frequency response
(40 to 500 Hz)

Influence of power
factor

Temperature
characteristics (in
range 0 to 40 ℃)

Maximum circuit
voltage

(Power meter) Single-phase active power

AC current and AC voltage (rms
reading)

(Integrator) Watthour value

Current: 2/20 A
Voltage: 0 to 250 V (resolution 1 V)

(Integrator) Lo: 200 W range 103/105Wh

Hi: 2000 W range 104/106Wh

(Power meter) Power: ±0.5% of rdg. ±0.3% of f.s.

Current: ±0.5% of rdg. ±0.3% of f.s.
Voltage: ±0.7% rdg. ±1 dgt.

(Integrator) ±1% rdg. ±1 dgt. (at input of 2.5% to

120% of f.s.)

(Power meter) Power: ±1% of max (power factor 1.0

Current, Voltage: ±0.5 % max

(Power meter) ±0.8% of rdg. max (power factor 0.5)

(Power meter) ±0.1% f.s./℃ max
(Integrator) ±0.05% f.s./ ℃ max

(Power meter) 250 Vrms

―――――――――――――――――――――――――――――――――――

Chapter 2 Specifications

4

―――――――――――――――――――――――――――――――――――――――

Rated current (Power meter) 15 Arms (continuous rating)
Crest factor (Power meter) Power, current: 2 max at maximum

display or 30 A peak (lower value)
Voltage: 500 V peak value max

Output terminals (Power meter) 2 VDC/f.s. 2 VDC output for 200 V

input in voltage function only.

(Integrator) Hi: 5V, Lo: 0 V CMOS level

External control
terminal

Dielectric strength AC 2.4 kV/1 min (between input terminals and case)
Power supply 100, 120, 220, 240 VAC ±15%, 50/60 Hz
Rated power Approx. 3.5 W
Effect of power supply

voltage
Backup power R6P manganese batteries×3 (supplies more than 100

Dimensions Approx. 218 (W) × 85 (H) × 240 (D) mm

Mass 2.6 kg
Accessories Power cord 1

Options 3171 DIGITAL PRINTER

(Integrator) OFF: Open (or Hi: 5 V)

ON: Closed (or Lo: 0V)

Specified accuracy satisfied within above specified
line voltage ranges.

hours backup capability)

(excluding protrusions)

Instruction Manual 1

9084 CARRYING CASE
9149 CARRYING CASE

―――――――――――――――――――――――――――――――――――

Chapter 2 Specifications

5

y

h

3

n

3

―――――――――――――――――――――――――――――――――――――――

Chapter

Principle of Operatio

.1 Power Measurement

Figure 3.1-1 and 2 show the block diagram. The line
voltage and current of the device under measurement are
detected by a voltage transformer (PT) and current
transformer (CT), respectively. The resulting detected
signals are voltage-level converted and input to a
multiplier. Since the DC component of the output of this
multiplier is proportional to the active power, after the
level is adjusted, this is displayed and output as the
power value.

Power suppl

To eac
section

Figure 3.1-1 The Block Diagram 1

INPUT

OUTPUT

PT

To V IN

To A IN

CT

―――――――――――――――――――――――――――――――――――

Chapter 3 Principle of Operation

6

e

n

o

s

r

e

n

3

it

3

it

r
r

Power output

Voltage output

Current output

To VF converter

V IN

A IN

r

z

e

Figure 3.1-2 The Block Diagram 2

)

)

θ

―――――――――――――――――――――――――――――――――――――――

Low-pas

filter

Rms

conversio

Rms

conversio

Division

(106)

1 s pulse 1 min pulse 1 h puls

6-digit

counter

Division

(60)

-1/2 dig
A-D

Decode

driver

Division

(60)

Multiplie

VF

converte

32.768 kH
Clock

oscillato

Auto-zer

Absolut

value

Absolut

value

Division

(215)

The voltage and current waveforms in Figure 3.1-3 are
described by equations and .

e = Ecosωt
i = lcos(ωt+θ

-1/2 dig
LCD

6-digit

LCD

Timer

9 9

P=Elcos

P=e･i=Elcosθ+ Elcos(2ωt+θ

Figure 3.1-3 Power Calculation Waveform

Sinewave AC voltage e = Ecosωt [V]
Sinewave AC current i = Icos(ωt+θ) [A]

The product of e and i representing the voltage-current
product is the instantaneous power.

Instantaneous power p = e･i = 2EIcosωt･cos(ωt+θ)

         = EIcos(2ωt+θ) + EIcosθ

           [W]

―――――――――――――――――――――――――――――――――――

Chapter 3 Principle of Operation

7

r

o

a

E

）

─────

3

―――――――――――――――――――――――――――――――――――――――

Thus, the active power P = EIcosθ [W] is the DC
component of the product of the voltage and current (the
second term in equation ( )).

.2 Current and Voltage Measurement

When measuring AC signals using a general-purpose
measuring instrument, an average-value detection is
performed, after which conversion to the rms value is
made. Therefore, measurements on distorted or other­wise non-sinusoidal waveforms will result in errors. In
the 3181-01, the true rms value is read by an absolute
value detection circuit and a true rms value conversion
circuit.

lnx

Ei（t）

lnx

＋

x

e

ー

L. P. Fadde

lnx

True Rms Conversion Circuit

In the true rms conversion circuit shown in the figure
above, if we observe point a, we find the following
relationship.

─────

ln Ei（t）

──────

ln Ei2（t）

∴ Eo =

────

+ln E（t）

=lnEo

2

i2（t

- ln Eo = ln Eo

Now let Ei(t) be the result of performing absolute-value
detection on the voltage and current signals from the
voltage transformer and current transformer, then the
output voltage Eo is proportional to the voltage-current
rms value.

―――――――――――――――――――――――――――――――――――

Chapter 3 Principle of Operation

E

8

3

―――――――――――――――――――――――――――――――――――――――

.3 Integrated Watt Value

The DC voltage Ei(2 V f.s.) is proportional to the power
measured by the power meter. The V-F converter
converts Ei into a pulse train, the pulses are counted by
the counter and the result is displayed as the watthour

value. (V-F conversion rate α = 27.7....(Hz/V)) 

For example, if 100 [W] is the power measured in the low
range (200 [W] f.s.), the voltage Ei input to the V-F
converter is given by the following formula.

Ei = 2 [V](f.s.)×100 [W] /200 [W]= 1 [V]
The time-unit switch on the 3181-01 front panel is also
the integrator RANGE switch. If integration is
performed at Wh:Lo (TIME:MIN) for one hour, the
resulting integration value N is calculated thus:

N=α [Hz/V]×Ei [V]×T [s]

= 27.7.... [Hz/V]× 1 [V]× 3600 [s]

= 100000

By interlocking ranges and setting the decimal point at
the fourth digit from the right, it is possible to directly
display watthour values of up to 100.000 Wh. If
integration is performed for one hour with Wh:Hi
(TIME:HOUR) set, after the divide-into-100 circuit, the
following value is obtained:

N = 27.7.... [Hz/V]× 1 [V]× 3600 [s]× 1/100

= 1000
If the decimal point is set at the second digit from the
right in this case, the value 100.0 Wh is displayed. As
the above discussion shows, the maximum display value
of the integrator can be changed by different
combinations of time units and ranges (table on the next
page).

―――――――――――――――――――――――――――――――――――

Chapter 3 Principle of Operation