YOKOGAWA 51001 User manual

RG102
5th Edition
Apr. 2007
51001
Digital
Illuminance Meter
User’s
Manual

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CONTENTS
Overview ...................................................................................................... 2
Prior to Use................................................................................................... 3
Operation ...................................................................................................... 5
Illuminance Measurement .......................................................................... 11
Data Hold ............................................................................................. 12
Timer Hold ........................................................................................... 13
Range Hold .......................................................................................... 13
Deviation Display ................................................................................ 14
Data Output ................................................................................................ 16
Recorder Output (Analog Output).............................................................. 19
Separation of Light Detector ...................................................................... 20
After-sales Servicing .................................................................................. 21
Specifications ............................................................................................. 22
Characteristics of Relative Visible-spectrum Response............................. 23
Characteristic of Oblique Incident Light .................................................... 25
Illuminance Measurements for Lighting Installations
(Extract from JIS C 7612 standards) .......................................................... 26
Copyright Nov. 1994 (YG). 5th Edition: Apr. 2007 (KP)

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Overview
Thank you very much for purchasing our Digital Illuminance Meter. Prior
to its use, thoroughly read this instruction manual to observe the correct
way of use.
Our digital illuminance meter is a small, lightweight meter and enables
illuminance measurements with the meter separated from the light detector.
The display adopts a large liquid crystal display (LCD) for ease in reading,
and attention is also paid to operation key arrangement. The photoelectric
element adopts a silicon photodiode for correcting the spectral luminous
efficiency by combining with an optical filter in order to measure the
illuminance of natural light. There is a microcomputer incorporated in this
meter to realize an illuminance meter having excellent functions. There are
also various functions incorporated in this meter, not found in conventional
meters: a data-hold function; a timer-hold function; deviation display; an
automatic power-off function; a response selection function; and others.
Refer to the text for details on these respective functions. Moreover, this
illuminance meter provides recorder output and digital data output, further
extending its usefulness. Thus, the range of applications of this meter is
much more extensive than that of existing luxmeters (illuminance meters).
This digital illuminance meter has been designed, manufactured, and
delivered under strict quality control criteria by a factory certified in the
ISO 9001 Quality Standards. We hope you will be able to make sufficient
use of the performance of this product, in addition to our traditional
photocell luxmeters.
Please retain this instruction manual for future use in operating this product.

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Prior to Use
Checking accessories
After unpacking the meter, check it for appearance and its accessories.
Accessories: Instruction manual: 1
Recorder output plug (JC017A): 1
Soft-sided case (RB038A): 1
One dry cell battery (9 V) in the meter.
Precautions on Handling
·Exercise care not to drop the meter or hit it with a hard object.
·Avoid placing the meter in a room at a temperature above 60°C or below -
20°C. Also, avoid placing it in an area subject to direct sunlight or at a
high humidity.
·Using the meter at low temperatures (between -10 and 0°C) causes the
display response to be delayed.
·Avoid using the meter in a dirty, dusty, or salt-air area or where there are
corrosive gases.
·Dirt or dust adhering to the light-detecting surface decreases measurement
accuracy. Wipe the surface clean with a soft, dry cloth.
·Do not use solvent (trichloroethylene, paint thinner, benzene, alcohol,
etc.), which may deform the case material or cause the print to peel off.
To remove stains from the case, gently wipe them off with a soft cloth.
If the instrument is badly stained, use a soft cloth moistened with a neutral
detergent, then wipe off the moisture using a dry cloth.
·Do not disassemble the meter.
·Do not separate mainunit from light-detector with the power on.
Safety Summary
The CAUTION Which appear on the following page must be followed to
ensure operator safety and to retain the operating condition of the
Illuminance Meter,
Safety Symbol
Indicates the operator must refer to an explanation in this manual.

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Calibration
Calibrate the meter once every two years in order to maintain accurate
measurements. Calibration is done by Yokogawa. To have the meter
calibrated, consult the Yokogawa sales representative from whom you
purchased the instrument or the Yokogawa sales division listed on the
back of this manual.
Optional Accessories
SpecificationProduct
Light-detector extension cable
Data output cable
AC adaptor
Model
3m
30m
3m
120 V (DC 9V)
220 V (DC 9V)
910 01
910 02
910 03
940 01
940 02
Note
Accessories of non-standard
Safety standard: EN 61010-1
· AC adapter Model: 94001(Input of 120 V±10% AC)
Model: 94002(Input of 220 V±10% AC)
EMC standard:
· Light-detector extension cable
Model: 91002(Cable length: Approx. 30 m)
Danger of electrical shock!
·When you use the AC adaptor, never use a power supply that is not suited to
the adaptor.
·Handle the AC adaptor with care so that the adapter is not damaged. If the
adaptor is damaged, do not use it.
CAUTION

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Operation
Components
Cap
Light detector
Light-detecting surface
Display area
Main unit
Power switch
∆/% key
Range key
Hand strap
Data output connector AC adaptor input
Figure 1. Components

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Measuring reference plane indication
Tripod-mounting screw Recorder output
connector
Hold switch
Eject button
Rating nameplate
Battery cover Response selector
switch

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Display Area
Figure 2. All Display Elements (some are unused)
Description of Elements in Display Area
Display condition/indication
Digital display of measured value, calculated value, and set value
Indicates meter in automatic power-off mode
Deviation
Indicates when a plug is inserted into the recorder output connector
Indicates range hold
Indicates data hold and timer hold
Indicates low battery voltage
Response setup display
Unit of illuminance
Unit of illuminance
Deviation display (%)
Element
8,8.8.8,8.8.8
AUTO POWER OFF
∆
R–H
RSPS
lx
fc
%
REC
+ –
D–H

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Prior to Operation
1. Response Time Setup
The response speed of the light detector can be selected using the response
selector switch. The response speed is set as described below. Set the
switch to FAST or SLOW according to its application. When FAST is set,
[RSPS
F
] appears; when SLOW is set, [RSPS
S
] appears in the display
area.
Response speedSwitch position Application
Approx. 10 mS
Approx. 500 mS
Measurement of continuous light
Daylight, interior lighting (fluorescent
lamps, incandescent lamps), etc.
Measurement of average illuminance
such as flickering lights or variations
from measuring beams such as TV screens
FAST
SLOW
Note: If the recorder output is used for waveform observation, set the
switch to FAST
2. Replacement of Battery
If the battery voltage drops during operation, a [ ] sign appears in the
display area. In this case, replace the battery with a new one immediately.
Check the polarity markings in the battery compartment and battery’s
polarity in order to avoid putting in the battery incorrectly. Use either a
6F22 9-V dry cell battery (S-006P, manganese, with approximately a 25-
hour service life) or a 6LR61 9-V dry cell battery (alkaline dry cell battery
with approximately a 40-hour service life).
Battery cover
Battery
Main unit
Figure 3. Replacement of Battery

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3. Selection of Units of Measurement (lx, fc)
Since this illuminance meter conforms to the International System of Units
(SI units), the lux (lx) is regarded as the reference unit. Some countries use
the footcandle (fc) which is not an SI unit. For this reason, this illuminance
meter provides a function to display readings converted to fc units with a
unit selector switch. Select the desired unit, as needed, prior to measure-
ment.
Be sure to turn off the power before selection.
Figure 4 shows the location of the lx-fc selector switch. Note that the
specifications and operation description in this manual are based on the lux.
Figure 4. Location of lx-fc Selector Switch
4. Automatic Power Off (AUTO POWER OFF)
This digital illuminance meter provides an automatic power-off function in
order to avoid using up the battery if you forget to turn off the power. This
function turns the power off about 30 minutes after any key is last pressed.
Immediately before turning the power off, the meter makes a beeping
sound. If you press any of the operation keys while the beeping sound is
on, this will extend the time of the automatic power-off function by 30
minutes. Whenever a plug is in the recorder output connector while the

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totalized intensity of illumination and/or the comparator function is being
executed, this function is automatically disabled; thus, it does not function.
The function can be disabled permanently if not necessary (if the meter is
used continuously). Refer to the operation procedure described in “Illumi-
nance Measurement.” Whenever this function is operable, [AUTO
POWER OFF] appears in the display area.
Notice on Making Measurements
1. Before starting measurement, as a rule, turn on the bulb five minutes
beforehand and the discharge lamp 30 minutes.
2. Set the position and angle of the light-detecting surface accurately.
Figure 5 shows the measuring reference plane.
Measuring reference plane
Figure 5. Measuring Reference Plane
3. Exercise care that your position or clothes do not affect illuminance
measurement.
4. In the case of accurate illuminance measurement, multiply the measured
value by the color correction factor corresponding to the spectral
distribution of the measuring light source and the factor corresponding to
the relative spectral response of this illuminance meter, respectively.
This meter provides a color correction factor function which is set to a
typical light source. The color correction factor multiplied by the
measured value is indicated automatically.
5. The zero point may vary if the ambient temperature varies greatly over
long-time meter use. In such a case, turn off the power once and then
turn it on again (see “Illuminance Measurement”).

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Light source type Color correction factor*
Typical value of
Daylight fluorescent lamp
White fluorescent lamp
Three-way fluorescent lamp
0.994
0.996
1.007
High-pressure mercury vapor lamp 0.993
High-pressure sodium vapor lamp 0.988
Standard light source B
Standard light source C 0.996 0.995
Equal-energy source (400 to 760 nm) 0.997
*The color correction factor is calculated based on the relative spectral distribution values
respectively of JIS Z 8719, JIS Z 8720, and CIE No. 53TC.2 lamps.
Table 1. Typical Values of Color Correction Factor
· An electromagnetic interference affects the operating tolerances under
EN61326-1;1997+A1;1998 condition.
· If a high electromagnetic interference equipment exists in the near vicinity of
the instrument, this may cause malfunction.
Note
Illuminance Measurement
Operation
1. Cover the light-detecting surface with the cap and confirm that the
HOLD
switch lock is released.
2. Press the
POWER
switch to turn on the power. All the characters will
appear in the display area. When the meter enters the automatic zero-
adjustment mode, [—CAL—] appears.
Note: If [—CAP—] appears, this means that the cap is not on properly.
Press on the cap until [—CAL—] appears.

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3. When automatic zero adjustment is completed, [—CAL—] disappears
and [0.0] appears.
4. After confirming the [0.0] display, remove the cap to start measurement.
5. After the measurement has been completed, press the
POWER
switch
again to turn off the power, and cover the light-detecting surface with the
cap for protection against stray light.
Note: If [Err] appears, check the connection between the main unit and
light-detecting surface and check the cap to make sure it is on
properly, and then start this operation again from the beginning. To
disable the automatic power-off function, press the
HOLD
switch
to lock the switch before turning off the power. When automatic zero
adjustment is completed, press the
HOLD
switch to release the
lock. [AUTO POWER OFF] disappears, resulting in automatic
power-off being disabled.
Figure 6. Example of Display upon Illuminance Measurement
Data Hold
HOLD
Switch
This function holds (locks) the measured value indicated. This switch is
used when it is hard to read an indication, such as measurement in a dark
place.
Operation
1. Press the
HOLD
switch (lock). The measured value is held (locked)
and
D–H
appears.

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2. Read the indication, taking the meter to a bright place or turning on a
light in the room.
3. To release the lock, press the
HOLD
switch again. This causes
D–H
to disappear.
Timer Hold
HOLD
Switch,
T–H
Key
This function holds the measured value after a time set in advance has
elapsed. You must move away from the place where the meter is located so
that your position or clothes do not have an influence on the measurement.
Setting and holding the time so you may leave the area enable accurate
measurement. The data are held (locked) after five seconds have elapsed.
Operation
1. Press the
HOLD
switch (lock). This causes
D–H
to appear.
2. Press the
T–H
key to start the timer;
D–H
starts blinking.
3. Move away from the place where the meter is located.
4. When five seconds elapse, a beeping sound is generated,
D–H
stops
blinking, and the measured value at that time is held (locked).
5. Read the indicated value.
6. To release the lock, press the
HOLD
switch again. This causes
D–H
to disappear.
7. To repeat this operation, do items 2 to 5 or 1 to 6.
Range Hold RANGE Key
This key selects automatic range and manual range. Manual range enables
an arbitrarily fixed range to be set. If measured values are known to be
within a particular range response comes fast if a fixed range is used,
making reading much easier.

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The range configuration is as follows:
0.0 to 99.9
0 to 999
0o to 9,99o
0oo to 99,9oo
0,ooo to 999,ooo
o: dummy display (The o or o’s indicate the number of digits)
Operation
1. Press the
RANGE
key to switch manual range; its range is fixed to the
currently executing range. This causes [R-H] to appear.
2. Each time this key is pressed, the range becomes maximized subse-
quently. After the display reaches the most significant range, it returns
to the least significant range, and repeats such action.
Note: To confirm the range, cover the light-detecting surface with the cap to
make the luminous intensity zero.
3. When the display shows the setting range, stop this key operation.
4. Keep pressing this key for two seconds to return to automatic range.
Deviation Display
∆/%
Key
This key is the deviation display function. The deviation is displayed by
setting the reference luminous intensity and calculating the deviation to the
set reference value. The display is twofold:
(1) Deviation value display ∆
∆= (measured value) - (reference value)
(2) Percent display
% = (∆/reference value) x 100

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Operation
1. Measure the reference luminous intensity and then press the
∆/%
key.
The measured value at that time is retained in memory as a reference
value. This causes [∆, R-H] to appear and the measured range is fixed.
After that, the deviation value is displayed.
2. Press the [∆/%] key again to change to the percent display. This causes
[%] to appear. Each time this key is pressed, these two appear alter-
nately.
3. To confirm the reference value, keep pressing the
CALL
key.
4. To release, press the
∆/%
key for two seconds.
Note: If the measured value exceeds the measuring range, [OL] appears.

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Data Output
Digital data output and comparator output can be transferred out through
the data output connector. The output data are illuminance measurement
data, which are transmitted as BCD serial data conforming to our standard
format.
Modular jack, 6 positions
Figure 7. Connector Pin Arrangement
Illuminance meter
External power supply: 3 V
Output level
Figure 8. Connection Circuit

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Figure 9. Timing Chart
Table 3. Contents of Data
Start bit
Measurement data overflow
Function-setting data hold
Measurement data sign (-)
Error
Lo batt (low battery voltage)
Data length (48 bits)
Model code
Measurement data
Unused
Unused
Measurement data 102
Bit Data Bit
Output
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
H
L
L
L
L
H
H
L
L
L
L
L
dp1
dp2
dp3
decimal point
8
4
2
1
Measurement data 101
Measurement data 100
Unused
Measurement
Display of unit lx
Unused
Bit Data Bit
Output
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
L
L
L
L
L
L
L
L
L
L
L
data exponent
8
4
2
1
8
4
2
1
10–6
10–3
10–3
10–6
The levels of L and H in bit output are fixed.
(illuminance meter)

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·The application of this accessory could affect the immunity performance of
the product and such items should be used with this consideration.
·Interconnection with other apparatus is not recommended.
Note

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Recorder Output (Analog Output)
Recorder output is connected to observation equipment (recorder, oscillo-
scope, etc.), and records of illuminance variation or a light source waveform
can be observed.
Specifications: 999mV ±5% (range fixed for full scale of each range) Load
resistance of 100 kΩor more
1. Prepare a coated single-core shielded wire and solder it to the attached
recorder output plug as shown in Figure 10. Connect another shielded
wire to the input connector of the observation equipment.
Shielded wire
Soldered on + side
Soldered on - side
Plug cover
Figure 10. Shielded Wire Connection Diagram
2. Turn on the power to the illuminance meter and insert the plug into the
recorder output connector of the light detector. The display [
REC
, R-
H] appears, and the range is fixed (manual range).
3. Set the response selector switch to FAST.
4. The output voltage is 1 mV for one numeral of the least significant digit
of the effective display (3 digits). Confirm the range according to the
illuminance-measuring range. Use the
RANGE
key for range setting.
Note: Refer to “Range Hold” for
RANGE
key operation.
5. Cover the light detector with the cap to adjust the zero level of the
observation equipment.
6. Remove the cap from the light detector to start observation.
·The application of this accessory could affect the immunity performance of
the product and such items should be used with this consideration.
· Interconnection with other apparatus is not recommended.
Note