The following general safety precautions must be observed
during all phases of operation, service and repair of this
instrument. Failure to comply with these precautions or with
specific WARNINGS given elsewhere in this manual violates
the safety standards of the design, manufacture and intended
use of the instrument.
YOKOGAWA assumes no liability for the customer’s failure to
comply with these requirements.
This manual is part of the product and contains important
information. Store this manual in a safe place close to the
instrument so that you can refer to it immediately.
Keep this manual until you dispose of the instrument.
The 2042 instruments are shipped only after stringent inhouse inspection. Should the instrument suffer damage that
is attributable to improper manufacture or an accident during
transport, contact the sales representative from which you
purchased the product or your nearest YOKOGAWA sales
ofce.
All products of YOKOGAWA are guaranteed for a period of one
(1) year from the date of delivery.
YOKOGAWA will repair the product in question, free of charge,
if the product fails during the guarantee period for reasons that
These are used for the voltage connection.
The common terminal is marked with the voltage polarity “±”, and
the two other terminals are marked with their respective voltage
ratings.
Current Terminals:
One of the terminals is marked with “±” to show the polarity
relation to the voltage coil, and the two alternative current
terminals are marked with their respective current ratings.
Table of Range-multiplier Constants:
The table is located on the side of the instrument case, and the
actual power value is obtained by multiplying the constant listed in
the table by the indication value on the scale.
Refer to the operational procedure for more information.
1. Do not use these instruments in a location exposed to direct sunlight, an
external magnetic eld or mechanical vibration or in a high-temperature
highly humid environment.
2. Place the instrument on a fairly level surface.
A horizontal position will give the highest accuracy.
3. When using a number of these instruments in an array, keep them as far
away from each other as possible.
4. Before wiring any of these instruments, carefully check the measuring
ranges and polarities. When wiring, securely fasten the terminals.
When a large current needs to be measured, use wire that is both thick
enough and has sufcient current-carrying capacity.
5. Before measurement, check that the pointer coincides exactly with the
zero scale point. If it does not turn the zero adjust screw provided on
the meter cover until the pointer meets the zero scale point.
Position your eye so that the mirror image of the pointer coincides with
the actual pointer. However, if the pointer is off from the zero scale
point because the pointer is bent, do not adjust using the zero adjust
screw because this will lead to errors.
6. Be careful not to apply an unreasonably large current or high voltage to
the instrument.
7. For the optimum instrument accuracy, select a measuring range such
that the indication may be read in the top half of the scale.
8. Try not to apply too much force when wiping the glass window surface
of the instrument during measurement. Doing so, may result in a
deviation in the indication due to static electricity.
This is especially true when the instrument is used in a dry season.
If the surface is dirty, clean it gently with a dry soft cloth.
To minimize the external magnetic field influence on the DC power
measurement, use the mean value of the power levels measured when the
terminals are connected as shown in Figure 2-5 or 2-6.
(1) For an accurate measurement, use the voltage terminal whose rated
value is closer to the circuit voltage. If the load current is unknown,
connect the circuit to the current terminal rated largest initially.
Then apply power to the circuit.
Both voltage and current ranges are changed by selecting terminals.
The ratio of the voltage ranges is 2:1.
The ratio of current ranges is 5:1.
(2) When using a current transformer, be sure not to open the secondary
circuit of the CT when changing the current range.
If the CT is provided with a switch to short the secondary circuit,
close the circuit using the switch before changing the measuring
range. If such a switch is not provided, you can either switch off the
power source before proceeding with the change or you can follow the
alternative wiring method for changing the range.
In this method, you use another leadwire to connect between the circuit
terminal to which the existing leadwire is connected and the CT current
terminal to be used for the new measuring range. Leave the existing
leadwire connected all during this procedure. Once the new terminal is
connected, you can disconnect the existing leadwire from the original
The multiplier constant table is attached to the side of the instrument, and
is used to obtain the actual measuring power from the reading on the scale.
In other words, the actual power is calculated from equation 1.
The range multipliers depend on the voltage and current range settings and
are calculated from equation 2.
Voltage range
Current range
1 A
5 A
Multiplier constant
120 V
2
10
240 V
4
20
IM 2042-01
— 8 —
2 × rated current (A) × rated voltage (V) × rated power factor (1.0)
=
Example:
Instruments with a rated current of either 1 A or 5 A and a rated
voltage of 120 V or 240 V.
The value indicated on the wattmeter is the sum of the load power and
the consumed power of the coil (current or voltage coil) connected to the
load side. If high accuracy is desired or the rated power of the wattmeter is
small (less than 1 kW), the power consumed by the coil must be subtracted
from the indicated value.
(1) Compensation when the voltage coil is connected to the load side:
• The connections for a power source with low impedance or for a
relatively small load power are as shown in Fig. 3-1.
The power consumption of the voltage coil in this case is almost the
same as the value indicated on the scale with no load.
Subtract this value from the rst readout to obtain the true load power.
電源
R
S
T
電源
S
負荷
Load
T
Power Source
±
±
P2
±
±
MC
MC
FC
A
P1
負荷
A
P
3
MC: 電圧コイル Voltage Coil
FC: 電流コイル Current Coil
— 9 —
IM 2042-01
・ 電源インピーダンスが高い場合や負荷の大きな場合は,内部抵抗
P = W – V
1r1
1r1
2
2
の内部抵抗
P = W – V
1r1
1r1
Fig. 3-2
Power Source
Load
のわかっている電圧計を使用して,Fig. 3-2 の回路と計算式から求
めます。
(— + —) – V (— + —)
1
2
r
1
r
2
P: 負荷電力
W: 電力計の指示電力
V
, V2: 電圧計の指示電圧
1
r: 電力計の電圧回路抵抗
r
, r2: 電圧計r1, r
1
2
R
• If the power source impedance is high or the load power is large, the true
load power value can be obtained by connecting two voltmeters with
known internal resistances as shown in Fig. 3-2, and by performing the
following calculation.
2
(— + —) – V (— + —)
1
2
2
r
1
r
2
P: Load power
W: Power indicated on the wattmeter
V1, V2: Voltages indicated on the voltmeter
r: Voltage circuit resistance of wattmeter
r1, r2: Internal resistances of voltmeters 1 and 2
1. To ensure good measurements, keep the instrument free of dust,
moisture, and away from direct sunlight.
2. If an overload or excessive shock causes the accuracy of the instrument
to become doubtful, check several scale points and compare these
readings with an instrument which has been properly calibrated.
If the accuracy of the instrument is found to be different from its rating,
readjust the instrument.
NOTE
If any troubles occur in the instrument, contact your nearest
YOKOGAWA Sales office or sales agent.
10/15/30/50/100/250/300/500/750/1500 A
10/15/30/50/100/250/300/500/750/1500 A
500 A (500 AT)
0.5/0.75/1/1.5/2/3/5/7.5/10/15/20/30/50/75/100 A
Note 1: The maximum line voltages are as follows.
2241: 3450 V
2242: 6900 V
2244 (2243*): 250 V
Note 2: The instruments also have the following characteristics.
2241 and 2242: Equipped with screw terminals for the 10 A, 15 A, 30 A, 50 A and 100 A
750 A and 1500 A measuring ranges.
Note 3: 2243*: Class 0.1 instrument
Note 4: 2244:For current measurements only. Cannot be used for power measurements.
一次
Primary
220/440/2200/3300 V
15/30/50/75 V
100/200/300/500 V
3300/6600 V
二次
Secondary
5 A
5 A
5 A
5 A
二次
Secondary
150 V
150 V
110 V
* 受注停止製品
* Discontinued product
定格負担
Burden
15 VA
15 VA
15 VA
15 VA
定格負担
Burden
15 VA
15 VA
15 VA
— 15 —
IM 2042-01
Printed in China
Loading...
+ hidden pages
You need points to download manuals.
1 point = 1 manual.
You can buy points or you can get point for every manual you upload.