3 Phase Programmable

ISW 8300

3 PHASE PROGRAMMABLE

DIGITAL WATTMETER

User Manual

INSTRUMENTS ET SYSTEMES

ZI des Radars, 12 rue Diderot

91350 GRIGNY

tel. : 33 (0)1 69 02 31 56 Fax. : 33 (0)1 69 02 08 93

ISW 8300

ISW83GB.DOC 08200

Specifications (18°C - 28 °C)

Notes : V = measured value R = range

Voltage (true RMS)

Ranges : 15V 50V 150V 500 V

Resolution :10mV 10mV 100mV 100mV

Accuracy (45-500 Hz) : ±(0.2% V + 0.2% R)

Input resistance :4.8M 100pF

Manual or autoranging

Crest factor : max. 3 at full scale (1.5 at 500 V)

Overload : 1000 V peak

Current (true RMS)

Ranges : 0.5A 1.5A 5A 15 A (internal)

0.5A to 5000A with external transformer

(selectable ratio 1 to 1000)

Resolution :0.1mA 1mA 1mA 10mA (internal)

0.1mA to 1A (external)

Accuracy (45-500 Hz) : ±(0.2% V + 0.2% R)

Crest Factor : max. 3 at full scale (2 at 15 A)

Manual or autoranging

Overload : 30 A continuous, 60 A 1s

Active Power

Ranges :7.5W to 7500W (16 ranges)

7.5W to 2500kW with external transformer

Accuracy (45-500Hz) : ±(0.3% V + 0.3% R) (U and I > 1/10 of range)

Resolution : 1mW to 1W according to range

1mW to 1kW with external transformer

Apparent Power

Ranges :7.5VA to 7500VA (16 ranges)

7.5VA to 2500kVA with external transformer

Accuracy (45-500Hz) :determined by U and I accuracy (see formulas)

Resolution : 1mVA to 1VA according to range

1mVA to 1kVA with external transformer

Reactive Power

Ranges :7.5VAr to 7500VAr (16 ranges)

7.5VAr to 2500kVAr with external transformer

Accuracy (45-500Hz) :determined by U and I accuracy (see formulas)

Resolution : 10mVAr to 1VAr according to range

10mVAr to 1kVAr with external transformer

Power Factor

Display :-1.000 to +1.000 (plus sign indicates inductive power, minus sign indicates capacitive power)

Accuracy (45-500Hz) :determined by U and I accuracy (see formulas)

Safety :CEI 1010-1 Cat III 600 V

InterfaceRS232 (3 wires). Xon-Xoff. protocol

Transmission rate 1200/9600 Baud

All functions and ranges programmable

Power :230 V ±10 % , 50-60 Hz, max. 10 VA

Temperature

of utilisation10-40 °C RH < 80 %

Dimensions240 x 240 x 88mm (L x l x H)

Weightabout 1,5kg

Misc. : Simultaneous display of 4 parameters

(10mm LED display).

Beeper indicates overload.

OptionsOPW2 3 wide bandwidth isolated outputs (U, I or P according to display).

The primary quantities U (voltage) and I (current) are sampled and calculated. Voltage, current and active power have their own tolerance. The calculating formulas of the next page are necessary to calculate the tolerances of the secondary quantities as a function of the tolerances of the primary quantities.

Formulas

Freq = frequency of the signal N = number of samples (N >120)

Remark: The formulas which give apparent power, reactive power and capacitors are applicable only for sinusoidal voltages and currents.

Safety

INSTRUMENTS et SYSTEMES certifies that this instrument has left the factory in perfect working order, both in operation and safety.

This instrument has been designed and manufactured with great care to bring the user the best possible safety to the user. If the instrument no longer functions properly or is damaged, it must be immediately disconnected from the ac supply voltage, from the measured circuit voltages and returned for repair.

Opening, maintenance, repair and calibration must be carried out by qualified and approved personnel.

Warranty

Provided it is used under the recommended conditions, this instrument is guaranteed for a two year period against manufacturing defects and component failure. This warranty applies to material and workmanship. The instrument must be shipped back to an agreed repair center. It will be repaired or replaced without charge. Warranty repairs are made at the discretion of IES.

Maintenance

Your wattmeter does not need any specific maintenance. Whenever cleaning is necessary, use a soft material. Avoid water or liquids that may penetrate inside.

Operation

Carefully unpack the instrument and make sure that it was not damaged during transportation. Insert the power cord on the rear of the instrument and connect to the ac supply. Switch power on by means of the power switch located on the rear panel.

Symbols used

Indicates the possibility Refer to the user manual

of a dangerous voltage

Changing a fuse

Before you change a fuse, disconnect the instrument from all possible dangerous voltages!

The defective fuse must be replaced using a fuse of the same type and value.

Selectable Options

At start up, the instrument displays first the software version, the transmission rate of 1200 or 9600 Baud and finally selects the V function (Voltage measurement).

Buzzer

The buzzer indicates overrange conditions or manipulation errors. It can be switched ON or OFF (toggle) in the following way:

Switch OFF the instrument. Hold the V key in and switch ON. Release the V key when The V function is reached. The new state of the buzzer is kept in memory until you decide to change it.

RS 232 Transmission Rate (1200/9600 Baud)

Proceed in the same way as for the buzzer but press the A key before start up.

Input Terminals

The Input Terminals are located on the rear panel of the instrument. Each channel has separate terminals for voltage and current inputs. Voltage measuring circuits are isolated from current measuring circuits and isolated from channel to channel. Therefore, it is possible to measure the current in a “cold” or “hot” point.

The voltage and current terminals are marked “+” and “-“. This is to indicate the phase relationship between them. Connect the circuit so that a positive voltage on the “+” voltage terminal generates a positive current flowing through the “+” current terminal. Under these conditions the power dissipated into a resistance will be positive.

Bad wiring may lead to important errors in three phase systems !

NEUTRAL Terminal

All voltage circuits are differential. The instrument generates a virtual neutral which is the average voltage of the three phases. This potential appears on the neutral terminal. When the neutral of the three phase system exists, it must be connected to the NEUTRAL terminal. The reference of all measurements is then exactly defined.

Measurement of the same quantity on three phases

The display of the same quantity on three phases permits the comparison of these quantities (unbalanced system) and indicates the average value (or the sum) of the quantities. For example, when power (W) is selected, the display indicates the power of each phase and the total power.

The different quantities which may be displayed are:

- voltage (V)

- current (A)

- active power (W)

- reactive power (VAr)

- apparent power (VA)

- power factor(PF)

- power factor compensation capacitors (µF)

The fourth displayed quantity () represents the sum (W, VAr, VA) .

One Phase measurements

One phase measurements indicates - for the selected phase or for the total system- voltage (V), current (A), active power (W) and reactive power (VAr).

Voltage and current ranges

There are four voltage ranges and four current ranges. At power-up, autoranging is set (AUTO is lit). To change from AUTO to manual ranging, push the corresponding lever up or down. The first pressure switches AUTO off, further pressures switch the ranges up or down.

The voltage and current ranges are switched simultaneously on the three phases.

In AUTO mode, the ranged is switched up if at least one display is higher than 1600 counts (15V - 150V – 1.5A) or 5500 counts (50V – 0.5A - 5A).

The range is switched down if at least one display is lower than 1300 counts (500V - 50V - 5A) or 450 counts (150V- 1.5A- 15A).

Overrange is indicated by a bip and the display blinks (" - OL - "display .

A current or voltage overrange may lead to the impossibility to calculate a quantity (e.g. power) . This is indicated as " - - - - - ". The reason of overrange must be cancelled. Select VOLT or AMP function to see which quantity overranges.

Current measurements with an external transformer

Measuring currents with an external transformer is specially useful:

- to increase the current capacity to 5000 Amps transformer ratio 1000:1

- to perform current measurements by means of a current probe. It is not necessary to open the circuit to insert the current measurement

Any current range is available for external measurements. The selected range must however be compatible with the output current of the transformer. For example, for a transformer with a nominal 5A output, select the 5A range. For a transformer delivering 1A, select the 1.5A range.

Connect the outputs of the current transformer to the current inputs of the wattmeter

Take care when you connect the transformer, to respect the phase relationship between current and voltage across the load. You can perform a quick check by connecting a resistive load. The measured power should be positive. I the power is negative, invert the current inputs.

To use an external current transformer

Place the CURRENT PROBE switch on the rear panel in the EXT position.

.

Select the appropriate current range

Select the set n function.

With the + and – keys, adjust the transformer ratio to the desired value.

Enter the value OK.

Note: the set n function can be set

Only in the current probe switch is in the EXT position.

The current ratio is the ratio of the primary current to the secondary current. It is an integer which may be comprised between 1 and 1000. The same current ratio is applied to the three phases.

The use of an external transformer is pointed out on the front panel by the EXT indicator.

Power measurements

With separate circuits to measure current and voltage, a lot of configurations are possible to determine the power absorbed by a load, or the power supplied by each phase.

Take a lot of care when connecting the circuit, to the place of the current measurements. In three phase systems the currents issued by each phase are summed and generate components which are not in phase with the input voltages.

Improper wiring may lead to wrong results like measurement of reactive power in a purely resistive circuit.

This is always true when external current probes are used. The probes prevent from opening the circuit but must be place in the right way.

STAR CONFIGURATION

TRIANGLE CONFIGURATION

THREE WATTMETER METHOD

When the load is not balanced, the total power will be measured by means of the three wattmeter method. If the neutral connection is not available, the artificial neutral ( N black plug) may be used.

The total power is displayed as :

P = P1 + P2 + P3

TWO WATTMETER METHOD

In 3 wires networks (without neutral), the two wattmeter may be used. The total power is displayed as :

P= P1 + P2

Single phase measurements

The synchronization signals needed for the measurement are always supplied by phase 1 (PH1). Therefore :

In single phase measurements, always use phase 1 (PH1).

Single phase measures do not put particular problem. On the other hand, the fact of using a three phase wattmeter with separate circuits allows unusual measurements as :

• Measurement of three powers and total power
• Comparison of powers
• Difference of powers

To measure the power applied to three different loads, connect the voltage inputs in parallel and each ammeter to a load (see drawing). The three powers and the sum appear on the four displays (W, VAr or VA function). Of course it is also possible to display the currents.

To measure a difference of powers, it is just necessary to invert an ammeter in series with one of the two loads. The displayed power becomes negative and the fourth displays indicates the difference.

X1000 indicator

All power measurements are displayed in W (active power), VA (apparent power) or VAr (reactive power).

When the measured value does not fit in the display, the X1000 indicator lights. The displayed values must then be multiplied by 1000, which is equivalent to a display in kW, kVA or kVAr.

Power factor

The power factor is defined as the ratio :

PF = Active Power / Apparent Power

The power factor is always positive and smaller than 1.

The only knowledge of the value of the power factor does not inform about the phase shift between voltage and current (lead or lag), that is the inductive or capacitive character of the power. That is why, a sign is added to the power factor. By agreement:

When the power factor is negative, the power is capacitive. When it is positive, the power is inductive.

Compensation capacitors

The compensation capacitors are used when the power absorbed by an installation has an important inductive component (transformers, engines …).

The calculation of their value lies on the knowledge of the reactive power with pure sine waves. Currents are rarely perfectly sinusoidal because of the usually poor linearity of inductive materials. The optimal value of the capacitors may be slightly different of the displayed values.

A negative capacitor, while wiring is correct indicates that the reactive power is already capacitive.

To measure voltages and currents

The ISW8300 Wattmeter measures alternating voltages and currents with a frequency comprised between 20Hz and 10000 Hz in three phase or single phase systems.

Single phase measurement must always be conducted on the phase 1 (PH1).

The internal synchronization signals are always supplied by the phase 1. If another channel is used or if the voltage or current is too small, the readings will be unstable.

The voltage measurement is differential. The red ( + ) and black ( - ) plugs may be inverted without any danger. The “polarity” of the input terminals is useful only to keep the right phase between voltage and current in power measurements.

The voltage input of the three channels are isolated from one another.

Current inputs are also symmetrical, isolated from one another and isolated from voltage circuits. Therefore, the current may be measured anywhere in the circuit.

Caution : the current inputs have a very small resistance of only a few milliohms, nearly a short circuit. Take care when connecting the circuit that the protective elements (fuses, circuit-breakers) are in a correct state of safety.

The voltage and current inputs may be overloaded without damage, even on the most sensitive ranges.

At start up, the instrument selects autoranging for voltage and current. When no power is connected to the inputs, the most sensitive ranges are connected. The choice of a particular range is useful to examine (for example with the analogue isolated outputs), the start-up current of a motor. The whole start sequence is not disturbed by the range switching.

Remote control

To select the transmission rate

You have the choice between two transmission rates between the instrument and the computer, 1200 or 9600 Baud. The Baud rate is displayed during a short time at start up. To modify it, switch the instrument off, press the A key for a few seconds and switch power on. The new selected rate is displayed and kept in memory until a new change is done.

Connection

The dialogue between the computer and the wattmeter is accomplished by means of a software protocol (Xon-Xoff). The connection needs only a simple 3 wires cable (Rxd, Txd and signal ground).

The connecting cable can be terminated at one end with a 9 pin connector and at the other end with a 9 pin or 25 pin connector, this depends on the PC serial port connector. The following connections should be followed:

RS 232 cable

To check the communications

You can quickly and easily check the connection with the "TERMINAL" option of Windows™.

First, switch the instrument off and on to check the transmission rate. If you want to change it see section "To select the transmission rate".

Enter the Terminal mode under Windows™ (or execute the program Terminal.exe). Select the following configuration in terminal:

• TTY terminal emulation
• terminal parameters: LF => CR/LF for Input and Output
• communication parameters: transmission rate 1200 or 9600 Baud.
• 8 Bits, no parity, 1 Stop Bit, Xon-Xoff

Send the command *IDN?. The instrument sends back the string:

IeS ISW8300 Vxx , where Vxx is the hardware version number.

Commands

The commands are sent as a string of ascii letters and digits. No special symbol or space should be added. Once sent, the command is executed upon reception of the carriage return character (CR = Hex 13). In terminal mode, this character is transmitted by the ENTER key of the keyboard, along with the Line Feed character which is ignored.

Note: the commands may be written either in UPPER or lower case.

Some commands will force the instrument to answer. It is the case for the commands:

• *IDN? : identification
• VERSION? : software version
• STATUS? : configuration of the instrument (see § STATUS string)
• DATA? : all measurements are sent
• VAL? : measured value. If the command arrives during the measurement cycle, the result will be sent only at the end of the cycle.
• VAS? status and measured value query
• MA1 : continuous output mode. Each result is sent to the computer. This mode is cleared by the MA0 command.
• N? : external current transformer ratio.

The table of the last page lists all the available commands.

STATUS string

Set N function

If the set N function (external current transformer setting) is active when a status string is requested, the status chain has the value :

"SETN".

For the other functions, the status chain sent back after reception of the STATUS? command has the following structure:

WATT AU1 AI2 x100

| | | |

function voltage current ext. Mode

VOLT AU: auto AI: auto xNNNN: ext. current transformer

AMP MU: manual MI: manual ratio NNNN

WATT 1: 15V 1: 0.5A

VAR 2: 50V 2: 1.5A

VA 3: 150V 3: 5A

KW 4: 500V 4: 15A

KVar

KVA

PF

CAP

PH1 (KPH1) *

PH2 (KPH2) *

PH3 (KPH3) *

SIG (KSIG) *

* K indicates that the active and reactive powers are expressed in KW and KVAr.

The different fields are separated with one or more spaces.

Measurement Result

The measurement result is transmitted :