CNPA 200
Page 1 of 6 pages
Technical Specification for Type
Approval of Illuminance Meters
S/N
CNPA 200
Rev.
1
1. This Technical Specification is developed pursuant to Paragraph 3, Articles 25 of the Weights
and Measures Act.
2. The date of promulgation, document number, date of enforcement and content of the
amendment are listed as follows:
Revision
Date of
Promulgation
Document No.
(Ching-Piao-Szu-Tzu)
Date of
Enforcement
1
18.06.2003
No. 09240005630
01.07.2003
Date of Promulgation
18.06.2003
Bureau of Standards, Metrology and
Inspection, Ministry of Economic Affairs
Content of Amendment
Date of Enforcement
01.07.2003
NO GUARANTEE ON THE TRANSLATION
In case of discrepancies between the English translation and Chinese text, the Chinese text shall govern.
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CNPA 200
Page 2 of 6 pages
1.
Scope: This Specification shall be applied to the type approval of illuminance meters having
illumination below 1500 lx.
2.
Construction:
2.1
The measuring unit of illuminance meter is “Lux,” expressed by the symbol of“lx.”
2.2
The following items shall be indelibly marked on an easily visible position of each
illuminance meter to avoid misrecognition:
(1) Class (AA, A or B);
(2) Type and serial number;
(3) Manufacturer’s name or trademark; and
(4) Measuring range of illuminance (if there are two and more measuring ranges, they shall
be labeled separately).
2.3
The light-receiver can be spearated from illuminance meter in application. Both of the two
parts shall be labeled by identical serial number and manufacturer’s name or trademark.
2.4
If the illuminance meter is equipped with a removable light attenuation filter, the same serial
number shall be labeled on the illuminance meter and light attenuation filter and a protective
cover shall be provided. Whenever the filter is taken off and put back again, the relative
position of the two parts shall be maintained.
2.5
The displaying mechanism of the body of an illuminance meter shall be able to be adjusted
and zero-setting.
2.6
The displaying mechanism of the body of an illuminance meter shall have a difference in
illumination values, between horizontal position and any other position 30 degrees inclined
from horizontal axis, that does not exceed the number of 2% of the maximum indicating scale
in the measuring range.
2.7
The minimum scale intervals shall be no greater than 2% of the maximum indicating scale in
the measuring range for analog illuminance meters, and no greater than 1% of the maximum
indicating scale for digital illuminance meters.
2.8
If the illuminance meter is battery-powered, it shall indicate the rated voltage and display the
state of insufficient power.
3.
Performance test
3.1
If the illuminance meter is energized by battery, when imposing voltage deviation to the meter
under effectively activated voltage range (to be exposed to a light radiant strength equivalent
to two thirds of the maximum measuring range), the deviation between the maximum and
minimum displaying values shall not exceed 0.5% of the maximum displaying value. If the
illuminance meter is energized by alternating current supply, when imposing voltage
deviation to the meter under 10% rated voltage range (to be exposed to a light radiant strength
equivalent to two thirds of the maximum measuring range), the deviation between the
maximum and minimum displaying values shall not exceed 0.5% of the maximum displaying
value.
3.2
After the illuminance meter has been exposed to a light radiant strength equivalent to two
thirds of the maximum illumination value of the measuring range, the display value that
degrades the illumination to zero by constant rate shall not exceed 1% of the maximum
illumination value of the measuring range.
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CNPA 200
Page 3 of 6 pages
3.3
The illuminance meter that has been exposed to a light radiant strength from zero to
equivalent to one half of the maximum illumination value of the measuring range shall
display the illumination value within 5 second.
3.4
When the light receiver has received and displayed the illumination equivalent to two thirds
of the maximum illumination value of the tested range, the display values between 1 minute
and ten minutes shall not be greater than 1% of the 1-minute display value.
3.5 Put the illuminance meter at 0ºC, 10ºC, 23ºC, 30ºC and 40ºC separately. After having
achieved a heat-balanced state, the illuminance meter is exposed to an illuminance equivalent
to two thirds of the maximum illumination value of the measuring range for one minute; the
display value (if a temperature compensation table is attached, use the value after temperature
compensation) deviated from the value at 23ºC shall not exceed the value listed in Table 1.
Table 1
Class
Deviation of display value
AA
±3%
A
±5%
B
±5%
3.6
The difference of display values of the illuminance meter, at the condition of 23±2ºC with
relative humidity between 45% and 75% (hereinafter referred to as the “normal relative
humidity”) and at the condition of return to normal relative humidity after having been
exposed to an atmosphere with relative humidity at 85%-95% (no condensate is formed) for
three hours, shall not be greater than 3% of the display value before the operation.
Measurement of the display value shall be performed before and after the operation under
the condition of normal relative humidity by having the illuminance meter exposed to an
illuminance equivalent to two thirds of the maximum illumination within the measuring
range value for one minute.
3.7
Emit parallel light beam in the strength approaching to maximum scale to the base surface of
light receiver. Rotate the base surface 30º, 60º and 80º relative to the two axes perpendicular
to each other and count the test value by using the formula defined below. The calculated
result shall not exceed the error defined in Table 2.
E  E 0C O S
E 0C O S
1 0 0
%
 = The rotated angle.
Eo = The indicated illumination when  is zero degree.
E = The indicated illumination after rotated  angle.
Table 2
Rotated angle
30º
60º
80º
Class AA
Error
±2%
±7%
±25%
Class A
Error
±3%
±10%
±30%
3
Class B
Error
±3%
±10%
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CNPA 200
Page 4 of 6 pages
If the illuminance meter is equipped with a removable light attenuation filter, it shall comply
with the values defined in Table 2.
3.8
Under the relative spectrum responding equipment, perform test for each 5 nm within the
wavelength of 380nm-780nm and calculate the measuring values by using the formula
defined below. The calculated results should not exceed the value defined in Table 3.
780
 S * ( )  V ( )

380
780
 V ( )
 100%
 380
S*(λ): The normalized relative spectrum response according to the equation defined below.
7 8 0
 I ( )  V ( )

3 8 0
7 8 0
 I ( ) S ( )
 S ( )
 3 8 0
I (λ): The spectrum strength of black radiation when the surface temperature is 2856 K.
S(λ): The relative spectrum response of surface-receiver.
V(λ): The visual efficiency of spectrum.
Table 3
Percentage of
Class
3.9
calculated value
AA
±8 
A
±16 
B
±24 
After the illuminance meter is exposed to ultraviolet zone, the value calculated from the
following formula shall not exceed 1%.
EUV  EUV
E0
 R
1 0 0
%
EUV:
The display value when a filter is attached for transmitting only ultraviolet radiation.
EUV-R: The display value when a filter is attached for transmitting both the ultraviolet
radiation and the long wavelength.
Eo:
The display value when no filter is attached.
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CNPA 200
Page 5 of 6 pages
The temperature distribution of light-emitting source is from 3000k to 3200k. Any filter
allowing ultraviolet zone to go through will have the maximum spectral transmittance at a
wavelength near 360 nm and does not transmit a wavelength band from 420 nm to 650nm.
The cut-off wavelength of long wavelength in which a filter allows to go through is 620nm.
3.10 After the illuminance meter is exposed to ultrared zone, the value calculated from the
following formula shall not exceed the value defined in Table 4.
EIR
 100%
E0
EIR: The display value when a filter is attached for transmitting only ultrared radiation.
Eo: The display value when on filter is attached.
Table 4
Percentage of
calculated value
±1 
±2 
±5 
Class
AA
A
B
The temperature distribution of light-emitting source is from 2846k to 2866k. The cut-off
wavelength of ultrared radiation in which a filter allows to go through is 800nm.
3.11 The linear error of light receiver for digital illuminance meter shall not exceed 0.3%. The
test procedure is illustrated below:
The value is measured first by having the light receiver receive the illumination equivalent to
the maximum illumination value of the measuring range, and measured again by having the
light receiver receive 1/10 of the former illumination value.
Calculate the linearity of light receiver from the following formulation:
E1  E 0  10
E 0  10
 100%
E1: The value when the light receiver has received the illumination equivalent to the
maximum illumination value.
E0: The value when the light receiver has received 1/10 of the former illumination value.
3.12 The digital illuminance meter circuit shall carry a linear error no greater than 1%. The test
procedure is illustrated below:
Expose the light receiver to illumination equivalent to the maximum illumination value and
measure the output current or voltage. Then expose the light receiver to illumination
equivalent to 1/3 and 2/3 of the maximum illumination value respectively, and measure the
output current or voltage again.
Calculate the linearity of illuminance meter circuit from the following formulations:
O 3  O1  3
O1  3
 100%
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CNPA 200
Page 6 of 6 pages
O3  O 2  1.5
O 2  1.5
O3:
 100%
The output current or voltage when the light receiver is exposed to illumination
equivalent to the maximum illumination value.
O1, O2: The output current or voltage when the light receiver is exposed to illumination
equivalent to 1/3 and 2/3 of the maximum illumination value respectively.
3.13 The switch error of test range for digital illuminance meter shall not exceed 0.2%. The test
procedure is illustrated below:
In two adjacent test ranges, measure the circuit’s output values when the light receiver is
applied by the output current and voltage that could allow the circuit to achieve the maximum
value of each test range.
Calculate the switch error of measuring range for digital illuminance meter from the
following formulation:
On  On  1  Kn
On  1  Kn
On:
On-1:
Kn:
 100%
In two adjacent test ranges, the circuit output of the test range that is wider.
In two adjacent test ranges, the circuit output of the test range that is narrower.
In two adjacent test ranges, the constant ratio of the maximum scale value of the
wider test range over the maximum scale value of the narrower test range.
3.14 The illumination value displayed by the illuminance meter shall not exceed the percentage of
the maximum value in test range shown in Table 5. The test procedure is illustrated below:
Apply three illuminations that pass through the center of the test base of the illuminance meter.
Compare the illumination values measured from the vertical direction after having the test
based exposed to light for one minute with the one calculated from the standard piece.
Table 5
Class
percentage of the maximum
value in test range
AA
±4 
A
±7 
B
±10 
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