Newtons4th PSM3750 NumetriQ User Manual
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Newtons4th PSM3750 NumetriQ User Manual

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PSM3750 - NumetriQ
USER MANUAL
th
Version 1.10 06
April 2017

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  • Page 1 PSM3750 - NumetriQ USER MANUAL Version 1.10 06 April 2017...
  • Page 2 “ Do not be hasty when making measurements.” NumetriQ is a precision instrument that provides you with the tools to make a wide variety of measurements accurately, reliably, and efficiently - but good metrology practice must be observed. Take time to read this manual and familiarise yourself with the features of the instrument in order to use it most effectively.
  • Page 3 DANGER OF ELECTRIC SHOCK Only qualified personnel should install this equipment, after reading and understanding this user manual. If in doubt, consult your supplier. RISQUE D'ELECTROCUTION L'installation de cet équipement ne doit être confiée qu'à un personnel qualifié ayant lu et compris le présent manuel d'utilisation.
  • Page 4 – do not attempt to open the instrument, refer service to the manufacturer or his appointed agent. Note: Newtons4th Ltd. shall not be liable for any consequential damages, losses, costs or expenses arising from the use or misuse of this product...
  • Page 5 PSM3750 user manual DECLARATION OF CONFORMITY Manufacturer: Newtons4th Ltd. Address: 1 Bede Island Road Leicester LE2 7EA We declare that the product: Description: Phase Sensitive Multimeter Product name: NumetriQ Model: PSM3750 Conforms to the EEC Directives: 2014/30/EU relating to electromagnetic compatibility:...
  • Page 6 In the event of any problem with the instrument outside of the guarantee period, Newtons4th Ltd. offers a full repair re-calibration service –...
  • Page 7 Detailed descriptions of the RS232 command set is given separate manual “PSM3750 communications manual”. Revision 1.10 This manual is copyright © 2017 Newtons4th Ltd. and all rights are reserved. No part may be copied or reproduced in any form without prior written consent. April 2017...

  • Page 8: Table Of Contents

    PSM3750 user manual CONTENTS Introduction – general principles of operation ..1-1 Generator output ............ 1-4 Voltage inputs ............1-5 Getting started ..........2-1 Unpacking .............. 2-1 Keyboard and controls ..........2-3 Basic operation ............2-4 Measurement Selectivity .......... 2-5 Using the menus ..........
  • Page 9 PSM3750 user manual Generator specifications ........... 8-3 Input channels ..........9-1 Trimming x10 oscilloscope probes ......9-5 10 True RMS Voltmeter ........10-1 10.1 RMS voltmeter specification........10-5 11 Frequency response analyser ......11-1 11.2 Quick start guide to Feedback Loop Analysis ..... 11-5 12 Phase angle voltmeter (vector voltmeter) ...
  • Page 10 PSM3750 user manual APPENDICES Appendix A Accessories Appendix B Serial command summary Appendix C Available character set Appendix D Configurable parameters Appendix E Contact details...

  • Page 11: Introduction - General Principles Of Operation

    PSM3750 user manual 1 Introduction – general principles of operation NumetriQ is a self-contained test instrument, with one output and two or three inputs, which incorporates a suite of test functions. NumetriQ has a wide bandwidth, isolated, generator output that can be used as signal generator for sine, square, triangle, or sawtooth waveforms, or true white noise.
  • Page 12 PSM3750 user manual FPGA This general purpose structure provides versatile hardware platform that can be configured by firmware to provide a variety of test functions, including: Signal generator Two channel true rms voltmeter Phase angle voltmeter (vector voltmeter) Frequency response analyser (gain/phase analyser) Harmonic analyser With additional external interfaces, such as current shunts, other functions are possible:...
  • Page 13 PSM3750 user manual The programmable nature of the instrument means that new functions can be added as they become available, or existing functions can be enhanced, by simple firmware download.

  • Page 14: Generator Output

    PSM3750 user manual Generator output The output sinewave is generated by direct digital synthesis (DDS). Amplitude is set in 2 stages - a fine control and a coarse control to give good resolution over the whole range. The output, has a variable offset added, is filtered and is buffered by a high speed, high current buffer.

  • Page 15: Voltage Inputs

    PSM3750 user manual Voltage inputs Each input consists of a pair of ac, or ac+dc, coupled high impedance buffers, one for the high voltages and one for lower voltages. The BNC safety connector and 4mm safety connectors are in parallel – either connector may be used. After the selectable heterodyning and filtering, there is a series of gain stages leading to an A/D converter.

  • Page 16: Getting Started

    PSM3750 user manual 2 Getting started The NumetriQ is supplied ready to use – it comes complete with an appropriate power lead and a set of test leads. It is supplied calibrated and does not require anything to be done by the user before it can be put into service. Unpacking Inside the carton there should be the following items: one NumetriQ unit...
  • Page 17 1.4V on all channels, each of which should indicate the 3V range; check that the gain reads 0.000dB 0.010dB, and that the phase reads 0.000 0.010. In the event of any problem with this procedure, please contact customer services at Newtons4th Ltd. or your local authorised representative: contact...

  • Page 18: Keyboard And Controls

    PSM3750 user manual Keyboard and controls The keyboard is divided into 5 blocks of keys: display control (5 keys top left) function keys (6 keys top right) setup keys (12 keys lower left) menu control keys (7 centre keys) action keys (4 keys lower right) In normal operation, the cursor keys give one-touch adjustment of various parameters, such as generator amplitude and frequency, without having to access the...

  • Page 19: Basic Operation

    PSM3750 user manual Basic operation The required function can be selected by pressing the function key, FRA, PAV, LCR, RMS, POWER, or SCOPE. Pressing the same function key again brings up the menu options specific to that function. For example, press PAV to select phase angle voltmeter mode;...

  • Page 20: Measurement Selectivity

    PSM3750 user manual Measurement Selectivity In many applications that require frequency response analysis, it is common for the frequency of interest (sometimes referred to as the injected frequency) to be immersed in noise. It is therefore important that the FRA instrument being used is able to reject frequencies other than that of the signal of interest.
  • Page 21 PSM3750 user manual While it is not required for the user to define the selectivity, nominal values used by the PSM units are defined in the following table: speed update rate normal time slow time Measurement constant constant Selectivity fast 1/20s 0.2s 0.8s...

  • Page 22: Using The Menus

    PSM3750 user manual 3 Using the menus NumetriQ is a very versatile instrument with many configurable parameters. These parameters are accessed from the front panel via a number of menus. Each of the main menus may be accessed directly from a specific key.
  • Page 23 PSM3750 user manual Pressing the HOME key first time reverts to the opening state where the parameters are displayed but the cursor is hidden. Pressing the HOME key at this point exits the menu sequence and reverts back to normal operation. To abort the menu sequence, press the HOME key twice.

  • Page 24: Selection From A List

    PSM3750 user manual Selection from a list This data type is used where there are only specific options available such as the output may be ‘on’ or ‘off’, the graph drawing algorithm may use ‘dots’ or ‘lines’. When the flashing cursor is highlighting the parameter, the RIGHT key steps forward through the list, and the LEFT key steps backwards through the list.

  • Page 25: Numeric Data Entry

    PSM3750 user manual Numeric data entry Parameters such as frequency and offset are entered as real numbers; frequency is an example of an unsigned parameter, offset is an example of a signed parameter. Real numbers are entered using the number keys, multiplier keys, decimal point key, or +/- key (if signed value is permitted).

  • Page 26: Text Entry

    PSM3750 user manual Text entry There are occasions where it is useful to enter a text string; for example, a non-volatile program may have some text as a title. Text is entered by selecting one of 6 starting characters using the main function keys on the top right hand side of the keyboard (FRA etc), then stepping forwards or backwards through the alphabet with the UP and DOWN keys.

  • Page 27: Special Functions

    PSM3750 user manual 4 Special functions Display zoom NumetriQ normally displays many results on the screen in a combination of small font size (no zoom) and up to 4 values in a larger font size (first zoom level). There is also an even larger font for up to 4 selected values (second zoom level).

  • Page 28: Program Store And Recall

    PSM3750 user manual Program store and recall There are 999 non-volatile program locations where the settings for the entire instrument can be saved for recall at a later date. Each of the 999 locations has an associated name of up to 20 characters that can be entered by the user to aid identification.

  • Page 29: Zero Compensation

    PSM3750 user manual Zero compensation There are 3 levels of zero compensation: Trim out the dc offset in the input amplifier chain. Measure any remaining offset and compensate. Measure parasitic external values and compensate. The trim of the dc offset in the input amplifier chain can be manually invoked at any time with the ZERO key, or over the RS232 with the REZERO command.

  • Page 30: Alarm Function

    PSM3750 user manual Alarm function NumetriQ has two independent alarms that can be read remotely or can generate an audible sound each of the alarms can be triggered by comparison to one or two thresholds: Sound the alarm if the value exceeds a threshold Sound the alarm if the value is below a threshold Sound the alarm if the value is outside a window Sound the alarm if the value is inside a window...
  • Page 31 PSM3750 user manual 1/3 of the measured value respectively. The repetition rate of the sounder then varies linearly as the value changes between these thresholds.

  • Page 32: Analogue Output

    PSM3750 user manual Analogue output The analogue output is a 0 to 10V dc level that represents the selected measurement. To program the analogue output, first select the functions for the zoom; up to four measurements can be selected for the display, the alarm is applied to any one of them;...

  • Page 33: Data Hold

    PSM3750 user manual Data hold When in real time display mode, the data on the display can be held at any time by pressing the REAL TIME key. When HOLD is activated a warning message is briefly displayed and the word HOLD appears in the top right hand corner of the display instead of the time.

  • Page 34: Results Store And Recall

    PSM3750 user manual Results store and recall There are 999 non-volatile storage locations that can store either real-time results or frequency sweeps. Each location can store the sweep results for up to 50 points. When storing a result, a text string may be entered to help identify the data.

  • Page 35: Using Remote Control

    PSM3750 user manual 5 Using remote control NumetriQ is fitted with an RS232, USB serial and LAN communications port as standard, and may have an IEEE488 (GPIB) interface fitted as an option. All the interfaces use the same ASCII protocol with the exception of the end of line terminators: Rx expects Tx sends...
  • Page 36 PSM3750 user manual commands that expect a reply are terminated with a question mark. NumetriQ maintains an error status byte consistent with the requirements of the IEEE488.2 protocol (called the standard event status register) that can be read by the mandatory command *ESR? (See section 5.1).
  • Page 37 PSM3750 user manual Commands are executed in sequence except for two special characters that are immediately obeyed: Control T (20) – reset interface (device clear) Control U (21) – warm restart maintain compatibility with some communication systems, there is an optional “protocol 2” which requires a space between the command and any arguments.

  • Page 38: Standard Event Status Register

    PSM3750 user manual Standard event status register bit 0 OPC (operation complete) cleared by most commands set when data available or sweep complete bit 2 QYE (unterminated query error) set if no message ready when data read bit 3 DDE (device dependent error) set when the instrument has an error bit 4 EXE...

  • Page 39: Serial Poll Status Byte

    PSM3750 user manual Serial Poll status byte bit 0 RDV (result data available) set when results are available to be read as enabled by DAVER bit 1 SDV (sweep data available) set when sweep results are available to be read as enabled by DAVER bit 2 FDV (fast data available (streaming)) set when data streaming results are available...

  • Page 40: Rs232 Connections

    PSM3750 user manual RS232 connections The RS232 port on NumetriQ uses the same pinout as a standard 9 pin serial port on a PC or laptop (9-pin male ‘D’ type). Function Direction in (+ weak pull up) RX data TX data not used not used NumetriQ will only transmit when CTS (pin 8) is asserted,...

  • Page 41: System Options

    PSM3750 user manual 6 System options Press SYSTEM to access the system options. The time and date are maintained by a battery backed real time clock. Time is expressed in 24 hour format. The display is normally in colour but it can be set to black on white or white on black.
  • Page 42 PSM3750 user manual environment where an operator has a small number of specific tests to perform. Most data is displayed to 5 digits but for extra resolution 6 digits can be displayed when in ZOOM level 2 or 3. When using external shunts or attenuators, the range can be shown either as the normal peak voltage or scaled by the shunt or attenuator factor.

  • Page 43: User Data

    PSM3750 user manual User data NumetriQ can be personalised by entering up to 3 lines of user data as text (see section on text entry). User data is displayed every time that the instrument is switched on to identify the instrument. The entered text may also be read over the communications to identify the instrument (see USER?).

  • Page 44: Measurement Options

    PSM3750 user manual 7 Measurement options ACQU - Acquisition options NumetriQ comes in 2 channel or 3 channel version. The 3 channel version can be set to display just 2 channels if the third channel is not in use. In normal acquisition mode the window over which the measurements are computed is adjusted to give an integral number of cycles of the input waveform.
  • Page 45 PSM3750 user manual The nominal values are: speed update normal slow time rate time constant constant very fast 1/50s 0.1s 0.4s fast 1/12s 0.4s 1.5s medium 1/3s 1.5s slow 2.5s very slow 10s 192s There is also an option to set a specific size of the window to a value other than the preset options.
  • Page 46 PSM3750 user manual The bandwidth of the instrument, usually set to “auto”, can be forced to “wide” or “low”. When not in auto selection, heterodyning is disabled and the bandwidth is either 5MHz (wide) or 100 KHz (low) to minimise noise when making measurements at low frequencies.

  • Page 47: Datalog

    PSM3750 user manual Datalog NumetriQ can store and display measurements recorded at regular intervals over a time period. Each data record consists of the elapsed time and up to four data values selected by ZOOM. The actual interval between data points is governed by the measurement speed and the datalog interval.
  • Page 48 PSM3750 user manual Note that in all cases the measurement interval is necessarily adjusted to be an integral number of cycles of the measured waveform. The datalog options are set up with the ACQU menu. The datalog is started with the START key, and stopped with the STOP key unless the store becomes full first.

  • Page 49: Sweep - Frequency Sweep Options

    PSM3750 user manual SWEEP - Frequency sweep options All ac measurements using the NumetriQ generator can be swept across a frequency range. The start frequency, stop frequency and number of steps up to 2000 can be specified. The measurements are subjected to the same speed constraints set in the ACQU menu, but the filtering does not apply on each measurement point.
  • Page 50 PSM3750 user manual normal display functions are restored. This mode is automatically selected when a user defined window of less than 100ms has been set.

  • Page 51: Trim - Trim Function

    PSM3750 user manual TRIM - Trim function The trim function on NumetriQ is a powerful and versatile feature that allows closed loop control of the generator amplitude. It allows a specific measurement from CH1, CH2 or CH3, if fitted, and the generator output will be adjusted to maintain the measured voltage or current.

  • Page 52: Output Control

    PSM3750 user manual 8 Output control The output for the signal generator is digitally synthesised at an update rate of 150Msamples/s. With the output filtering, this gives a good sinewave waveform, even at 35MHz, while preserving very accurate frequency control. The output amplitude is controlled in 2 stages –...
  • Page 53 PSM3750 user manual the harmonic analyser and power analyser where UP and DOWN step the selected harmonic). The generator output may be set to be on, off, or dc only.

  • Page 54: Generator Specifications

    PSM3750 user manual Generator specifications General accuracy frequency 0.05% amplitude 5% (10% > 50MHz) accuracy (with amplitude 1% < 10MHz trim) output impedance 50 2% output voltage 15V peak Offset 10V peak maximum waveforms sine, square, triangle, sawtooth, pulse and white noise frequency 10uHz to 50MHz output control...

  • Page 55: Input Channels

    PSM3750 user manual 9 Input channels The two or three input channels are fully isolated from each other and earth. The two channels are controlled independently but sampled synchronously. Each input channel may be selected to be: direct external shunt external attenuator If the external shunt option is selected, the data is scaled by the shunt value (entered under the relevant channel...
  • Page 56 PSM3750 user manual range reference nominal full scale 3.16mV 10mV 10mV 30mV 31.6mV 100mV 100mV 300mV 316mV 3.16V 31.6V 100V 100V 300V 316V 500V 1000V Because of slew rate limitations of the input amplifiers, the maximum input signal that can be accurately measured varies with frequency: frequency max input level...
  • Page 57 PSM3750 user manual There is also an option to autorange ‘up only’ so that a test may be carried out to find the highest range. Once the highest range has been determined, the range can be set to manual and the measurement made without losing any data due to range changing.
  • Page 58 PSM3750 user manual invoke the input menu for channel 1 then press TRIG and the scale factor for channel 1 is computed so that channel 1 reads the same as channel 2. Note that when using external divider probes to increase the maximum input voltage it is important to use active probes if accurately measuring dc.

  • Page 59: Trimming X10 Oscilloscope Probes

    PSM3750 user manual Trimming x10 oscilloscope probes To minimise the loading effects at high frequencies, x10 oscilloscope probes can be used with NumetriQ. For optimum performance, the probes need to be trimmed to match the input capacitance of the instrument and the probes need to be corrected for gain errors.
  • Page 60 PSM3750 user manual To adjust for the tolerance within the probes (typically 1%), the main inputs can be scaled and the secondary inputs can be adjusted. Press OUT and set 1kHz sinewave, 2V amplitude; and press FRA to invoke frequency response analyser.

  • Page 61: True Rms Voltmeter

    PSM3750 user manual 10 True RMS Voltmeter The RMS voltmeter measures the total rms of the signal present at the input terminals to the bandwidth of the instrument (>1MHz). Care must be taken when measuring low signal levels to minimise noise pick on the input leads. The RMS voltmeter measures the elementary values: peak surge...
  • Page 62 PSM3750 user manual The dc present is given by: 2  dc = 1/2 v() d For a sampled signal, the formula becomes: i = n-1  dc = 1/n v[i] i = 0 Where n is the number of samples for an integral number of complete cycles of the input waveform.
  • Page 63 PSM3750 user manual In order to measure surge conditions, the maximum instantaneous peak value (unfiltered) is also recorded. It is important that NumetriQ does autorange while measuring surge – either set the range to manual or repeat the test with ranging set to up only. To reset the maximum, press START.
  • Page 64 PSM3750 user manual measurement is requested – this can be disabled in the SYSTEM OPTIONS menu if required. The ZOOM function can be used to select any combination of up to four parameters from the display. Note that the wideband nature of true rms measurements prevents the use of heterodyning so the frequency range of the measurement is limited to 5MHz.

  • Page 65: Rms Voltmeter Specification

    PSM3750 user manual 10.1 RMS voltmeter specification Channels 2 or 3 fully isolated Display 5 digits measurement true rms, ac, dc, dBm, peak, cf, surge. Coupling ac or ac+dc frequency DC to 5MHz (heterodyning not available) ac coupling cut off ~1.5Hz (–3dB) max input 500V peak input ranges...

  • Page 66: Frequency Response Analyser

    PSM3750 user manual 11 Frequency response analyser NumetriQ measures the gain and phase of channel 2 relative to channel 1 using a discrete Fourier transform (DFT) algorithm at the fundamental frequency. The DFT technique can measure phase as well as magnitude and is inherently good at rejecting noise –...
  • Page 67 PSM3750 user manual For a sampled signal, the formulae become: i = n-1  = 1/n v[i].cos(2ci/n) i = 0 i = n-1  = 1/n v[i].sin(2ci/n) i = 0 Where n is the number of samples for an integral number of complete cycles of the input waveform, and c are the number of cycles.
  • Page 68 PSM3750 user manual To look at differences in gain from a nominal value, an offset gain can be applied either manually or by pressing ZERO. Offset gain = measured dB – offset dB The filtering is applied to the real and quadrature components individually, rather...
  • Page 69 PSM3750 user manual comprises a single window without any filtering unless repeat sweep is selected. The top of the vertical axis for the graph is normally set to be the highest measured value during the sweep. The bottom of the vertical axis is normally either set to the lowest measured value or the result of the highest value less 20dB/decade of frequency.

  • Page 70: Quick Start Guide To Feedback Loop Analysis

    PSM3750 user manual 11.2 Quick start guide to Feedback Loop Analysis This section is aimed as a helpful guide to enable you to set up your PSM3750 with the aid of screenshots and instructions with respect to Feedback Loop Analysis. Setting Input Channels to be used.
  • Page 71 PSM3750 user manual Setting the Amplitude and Output to On. Action Result Press ‘OUT’ Output Control Menu appears Press ‘↓’ 3 TIMES Flashing Red Box appears around the Amplitude Setting Press ‘300m’ 300mv now appears in the Amplitude Option Press ‘ENTER’ 300mv is selected as the Amplitude Press ‘↓’...
  • Page 72 PSM3750 user manual Gain and Phase Margins: Enable / Disable Action Result Press ‘MODE’ Measurement Settings Control Menu appears Press ‘↓’ 7 TIMES Flashing Red Box appears around the Gain / Phase selection Press ‘→’ Flashing Red Box appears around disabled / enabled options Press ‘↓’...
  • Page 73 PSM3750 user manual Setting Channels 1&2 Input Ranges & Coupling Action Result Press ‘CH 1’ Channel 1 Control Menu appears Press ‘↓’ 5 TIMES Flashing Red Box appears around the Coupling selection Press ‘→’ Flashing Red Box appears around ac+dc, ac options Press ‘↓’...
  • Page 74 PSM3750 user manual Action Result Press ‘CH 2’ Channel 2 Control Menu appears Press ‘↓’ 5 TIMES Flashing Red Box appears around the Coupling selection Press ‘→’ Flashing Red Box appears around ac+dc, ac options Press ‘↓’ Select ac only Press ‘ENTER’...
  • Page 75 PSM3750 user manual Frequency Sweep Data Settings Action Result Press ‘SWEEP’ Frequency Sweep Control Menu appears Press ‘↓’ Flashing Red Box appears around the Sweep Start selection Sweep Start now requires setting Press ‘100’ 100 now appears in the Sweep Start Option Press ‘ENTER’...
  • Page 76 PSM3750 user manual Perform Sweep and Review. Action Result Press ‘SWEEP’ Frequency Sweep Control Menu appears Check Sweep data parameters (as Frequency Sweep screen ) Press ‘SWEEP’ Display returns to measurement screen Press ‘START’ Frequency Sweep will begin Press ‘GRAPH’ View all data from sweep, keep pressing Graph to view more results Press ‘TABLE’...
  • Page 77 PSM3750 user manual Screen Print Options. Action Result Press ‘COMMS’ Remote Settings Control Menu appears Press ‘↓’ 5 TIMES Flashing Red Box appears around the Screen Print selection Press ‘→’ Flashing Red Box appears around disabled, RS232, USB memory stick Press ‘↓’...
  • Page 78 PSM3750 user manual Frequency response analyser specification Frequency response (gain/phase) analyser frequency 10uHz to 50MHz (own generator) 20mHz to 5MHz (external source) max input 500V peak input ranges *300mV, *1V, *3V, *10V, *= High Voltage Attenuator. 500V, 300V, 100V, 30V, 10V, 3V, 1V, 300mV, 100mV, 30mV, 10mV, 3mV ranging full auto, up only, or manual...

  • Page 79: Phase Angle Voltmeter (Vector Voltmeter)

    PSM3750 user manual 12 Phase angle voltmeter (vector voltmeter) A phase angle voltmeter (or vector voltmeter, or phase sensitive voltmeter) measures the signal at one input compared to the phase of the signal at a reference input. The results may be expressed as magnitude and phase, or as separate in-phase and quadrature components.
  • Page 80 PSM3750 user manual A null meter display may be selected via the PAV menu to allow adjustment of a circuit for minimum phase or component. The parameter on the display depends on the selected component: parameter display null meter in-phase in-phase quadrature quadrature...
  • Page 81 PSM3750 user manual NumetriQ computes a multiplying factor that it applies to the start frequency for the specified number of steps. Note that due to compound multiplication it is unlikely that the end frequency will be exactly that programmed. The frequency sweep is initiated by the START key, and when completed the data can be viewed as a table or graphs or printed out.

  • Page 82: Phase Angle Voltmeter Specification

    PSM3750 user manual 12.1 Phase angle voltmeter specification Phase angle voltmeter (vector voltmeter) frequency 10uHz to 50MHz (own generator) 20mHz to 5MHz (external source) measurement type DFT analysis, and true rms measurements Magnitude, Phase, In-Phase & Quadrature components, TanΦ, In- Phase Ratio, LVDT (diff), LVDT (ratio), Rms, Rms Ratio phase resolution...

  • Page 83: Power Meter

    PSM3750 user manual 13 Power meter power meter measures total power fundamental power of the signal present at the input terminals to the bandwidth of the instrument (>1MHz). Above 5MHz, only the fundamentals are measured. One of the inputs must be configured as an external shunt input.
  • Page 84 PSM3750 user manual When the integrator function is activated, the following values are available: Elapsed time (in hours, minutes and seconds) Watt-hours (true and fundamental) VA hours (true and fundamental) average power factor (true and fundamental) Ampere hours (true and fundamental) The power dissipated in a load subjected to a periodic voltage, v(), with a current flowing a(), is given by: 2...
  • Page 85 PSM3750 user manual power factor = Watts/VA fundamental Watts = V real real quad quad harmonic Watts = VH x AH + VH x AH real real quad quad fundamental VA fund fund fund power factor / VA fund fund In power meter mode, the UP and DOWN key do not adjust the amplitude but step the harmonic number.
  • Page 86 PSM3750 user manual taken by the load, less any power generated by the load, such as during regenerative braking in battery systems. 13-4...

  • Page 87: Power Meter Specification

    PSM3750 user manual 13.1 Power meter specification Power meter current input External shunt or Voltage CT display 5 digits measurement W, VA, PF,V,A, - Total, Fundamental and Integrated, Power Harmonics coupling AC+DC, AC(<10VDC), AC(<500VDC) frequency DC & 10mHZ to 5MHz 5MHz to 50MHz (fundamentals only) ac coupling cut off ~1.5Hz (–3dB) max input...

  • Page 88: Lcr Meter

    PSM3750 user manual 14 LCR meter In LCR meter mode, channel 1 measures the voltage across the component under test, and channel 2 measures the current through it. To measure the current, channel 2 must be connected across an appropriate external shunt. The easiest way to use the LCR meter is with the ‘IAI –...
  • Page 89 PSM3750 user manual For “shunt” connection, shown above, the current is measured directly across the shunt using CH2 while the voltage across the Zx is measured by CH1. Notice that the positive inputs to both CH1 and CH2 are connected to the midpoint to minimise common mode loading effects.
  • Page 90 PSM3750 user manual NumetriQ measures the real and imaginary components at fundamental frequency using analysis described in the section on gain/phase analysis. The frequency may be taken from its own generator or from the circuitry under test. From the fundamental components of voltage, (a + jb), and those of the current, (c + jd), NumetriQ computes the complex impedance given by: = v / i...
  • Page 91 PSM3750 user manual If the parameter option in LCR menu is set to ‘auto’, NumetriQ will display capacitance or inductance according to the phase of the measurement. Alternatively, the display can be forced to capacitance, inductance or impedance. Capacitance is displayed with tan, inductance is displayed with Q factor, and impedance is displayed in its resistive + reactive form and as magnitude.
  • Page 92 PSM3750 user manual and select “phase adjust”. NumetriQ then applies a compensating vector rotation subsequent measurements. NumetriQ can operate either in real time mode at a single frequency where the measurements are filtered and updated on the display; or it can sweep a range of frequencies and present the results as a table or graphs.
  • Page 93 PSM3750 user manual The ZOOM function can be used to select up to four parameters from the display when in real time mode. It has no function following a sweep. Although it is most usual to use the NumetriQ generator when performing LCR measurements, there may be circumstances where this is impractical, for example measuring the inductance of a transformer primary...

  • Page 94: Nyquist Diagram

    PSM3750 user manual 14.1 Nyquist Diagram The PSM3750 can display impedance on either Bode or Nyquist plots. The Nyquist plot separates the Real and Imaginary components of impedance on an X-Y plot. To display a Nyquist plot, the PSM must be in LCR meter mode with the measurement parameter set to impedance as shown below: There two plotting parameters specific to the Nyquist plot:...
  • Page 95 PSM3750 user manual The axes are scaled to fit the sweep and a cursor is automatically displayed. The directional keys on the PSM’s front panel can be used to navigate the cursor. The following parameters are shown for the sweep step and are all updated by movement of the cursor: 1.

  • Page 96: Lcr Meter Specification

    PSM3750 user manual 14.2 LCR meter specification LCR meter frequency 10uHz to 50MHz (own generator) 20mHz to 50MHz (external source) measurement type DFT analysis measurements L, C, R (ac), Q, tan, impedance, phase, admittance series or parallel circuit conditions auto, or manual display numeric values table of sweep results...

  • Page 97: Harmonic Analyser

    PSM3750 user manual 15 Harmonic analyser The NumetriQ harmonic analyser computes multiple DFTs on the input waveforms in real time (refer to the chapter on frequency response analysis for the formulae for DFT analysis). There are three modes of operation: single harmonic, difference thd, and series thd.
  • Page 98 PSM3750 user manual The single harmonic and the thd are expressed relative to the fundamental either as a percentage or in dB, as selected via the HARM menu. NumetriQ can operate either in real time mode at a single frequency where the measurements are filtered and updated on the display;...
  • Page 99 PSM3750 user manual Although it is most usual to use the NumetriQ generator when making harmonic measurements, there may be circumstances where this is impractical, for example measuring harmonic currents drawn from the mains. In this case, turn off the NumetriQ generator (OUT menu) and the frequency reference for the analysis is measured from channel 1.

  • Page 100: Harmonic Analyser Specification

    PSM3750 user manual 15.1 Harmonic analyser specification Harmonic analyser fundamental 20mHz to 50MHz (own generator) frequency 20mHz to 5MHz (external source) harmonic 10uHz to 1MHz frequency measurement type multiple DFT analysis measurements single harmonic, differential thd, thd by series of harmonics max harmonic max input 10V peak...

  • Page 101: Transformer Analyser

    PSM3750 user manual 16 Transformer analyser The transformer analyser mode allows a comprehensive set of measurements to be performed on a transformer at a single frequency or automatically swept over a range of frequencies. The tests available are: turns ratio inductance leakage inductance ac resistance and Q factor...
  • Page 102 PSM3750 user manual The operating conditions for the component under test may be selected manually or for some tests (such as turns ratio) NumetriQ will automatically try to find appropriate conditions. NumetriQ can operate either in real time mode at a single frequency where the measurements are filtered and updated on the display;...
  • Page 103 PSM3750 user manual 16.1 Turns ratio Turns ratio is computed from the real part of the complex ratio of CH2 divided by CH1 using DFT analysis at the fundamental frequency (refer to the chapter on gain/phase analysis for the formulae for DFT analysis). This technique gives good results even on ‘lossy’...

  • Page 104: Inductance & Leakage Inductance

    PSM3750 user manual 16.2 Inductance & leakage inductance The inductance of a winding is computed from the complex ratio of CH1 (voltage across the winding) divided by CH2 (current through the winding) using DFT analysis at the fundamental frequency (refer to the chapter on gain/phase analysis for the formulae for DFT analysis).

  • Page 105: Ac Resistance And Q Factor

    PSM3750 user manual 16.3 AC resistance and Q factor AC resistance is measured the same way as inductance with CH1 monitoring the voltage across the winding, and CH2 monitoring the current through it via the external shunt (source resistance). The Q factor measurement is an effective way of detecting a shorted turn –...

  • Page 106: Interwinding Capacitance

    PSM3750 user manual 16.5 Interwinding capacitance The interwinding capacitance of a transformer is computed from the complex ratio of CH1 (voltage across the transformer) divided (current through transformer) using DFT analysis at the fundamental frequency (refer to the chapter on gain/phase analysis for the formulae for DFT analysis).

  • Page 107: Magnetising Current

    PSM3750 user manual 16.6 Magnetising current The magnetising current is the current drawn by the primary, energised under normal operating conditions but without any secondary load. It is typically measured on power transformers rather than signal transformers so although the transformer analyser fixture, TAF01, will select appropriate relays to make the measurement it is more common that a manual connection or a custom fixture would be used.

  • Page 108: Return Loss

    PSM3750 user manual 16.7 Return loss Return loss is a measure of impedance mismatch in signal transformers that are terminated with the design load resistance. The secondary winding is terminated with the appropriate load resistance and the primary is energised via a source resistance that is equal to the resistance that should be reflected back from the secondary (load resistance * (turns ratio)

  • Page 109: Insertion Loss

    PSM3750 user manual 16.8 Insertion loss Insertion loss is a measure of power loss due to impedance mismatch in signal transformers that are terminated with the design load resistance. The secondary winding is terminated with the appropriate load resistance and the primary is energised via a source resistance that is equal to the resistance that should be reflected back from the secondary (load resistance * (turns...
  • Page 110 PSM3750 user manual output and CH1 differential input across the series combination of the source resistance and the primary winding. Connect the appropriate load resistance and CH2 differential input across the secondary. When using transformer analyser fixture, connections for insertion loss are made automatically by relays.

  • Page 111: Harmonics And Distortion

    PSM3750 user manual 16.9 Harmonics and distortion Harmonic distortion introduced by a signal transformer may be measured either at a single spot harmonic or as the thd computed from a series of harmonics. The primary of the transformer is energised either by the output of NumetriQ or by external means and CH2 is connected across the secondary.

  • Page 112: Longitudinal Balance

    PSM3750 user manual 16.10 Longitudinal balance Longitudinal balance is a measure of the common mode rejection ratio, CMRR, of the transformer. Longitudinal balance requires external circuitry to give the required accuracy – a plug in module is available for the transformer analyser fixture,...
  • Page 113 PSM3750 user manual Transformer analyser specification Transformer analyser frequency 10uHz to 35MHz (own generator) 20mHz to 500kHz (external source) measurement type DFT analysis, true rms as appropriate measurements turns ratio turns inductance leakage inductance ac resistance dc resistance interwinding capacitance insertion loss return loss harmonics...
  • Page 114 PSM3750 user manual Appendix A – Accessories ACCESSORIES...
  • Page 115 PSM3750 user manual Power meter adaptors The power meter adaptors allow easy and safe connection of the NumetriQ to a mains appliance under test to measure the power or harmonics. The appliance under test plugs into an IEC mains outlet on adaptor, which contains...
  • Page 116 PSM3750 user manual 75 / 600 output adapter The generator output from the NumetriQ has a series impedance of 50. The output adapter fits directly onto the front of the instrument and provides 2 outputs: 75 via a BNC connector 600...
  • Page 117 PSM3750 user manual CommVIEW PC software CommVIEW is a self contained software program for a PC, which facilitates communication with NumetriQ over RS232. CommVIEW allows strings to be sent and received between a PC and NumetriQ. The strings can be viewed in a window and optionally stored in a file.
  • Page 118 PSM3750 user manual Appendix B – Serial command summary command format reply format *CLS *ESE,value *ESE? single integer data value *ESR? single integer data value *IDN? company,product,serial no,version *OPC? 0 or 1 *RST *SRE,value single integer data value *SRE? *STB? single integer data value *TRG *TST?
  • Page 119 PSM3750 user manual GAINPH GAINPH? freq,mag1,mag2,dB,phase GAINPH,SWEEP? n lines of GAINPH? data HARMON,scan,para,h,hmax HARMON? freq,mag1,mag2,hmag1,hmag2,h1,h2 freq,mag1,mag2,thd1,thd2,h1,h2 HARMON,SWEEP? n lines of HARMON? data HARMON,SERIES? mag1,%1,1,mag2,%2,2 1 line for each harmonic HOLD,on/off INPUT,channel,type INTYPE,channel,type INPUT,channel? single integer data value KEYBOA,value LCR,conditions,param,head LCR? freq, mag1, mag2, impedance, phase, R, L, C (series), R, L, C (parallel), tan, Q, reactance...
  • Page 120 PSM3750 user manual RANGE,ch,ranging,range RESOLU.format REZERO SCALE,channel,factor SCALE,channel? single real data value SHUNT,channel,resistance SHUNT,channel? single real data value SINGLE,on/off SPEED,speed[,window] SSWEEP,function,number START STATUS,channel? range number,range text,over/low/ok STOP STREAM,enable,window STREAM,disable STREAM? data, data, data, data, data, ….. SUSPEND,on/off TFA? freq,mag1,mag2,dB,phase TFA,SWEEP? n lines of GAINPH? data TXA,test,fixture,load,source TXA?

  • Page 121: Calibration Commands

    PSM3750 user manual calibration commands CALAPP CALCOM,freq CALFIL,index,value CALFIL? six real data values CALFRQ,index,freq CALFRQ? seven real data values CALIBR,index,value CALIBR? single integer data value CALOUT,index,value CALPHA,index CALRES CALSAV,password CALSNO,serial number CALSTR,string CALSTR? string...
  • Page 122 PSM3750 user manual Appendix C – Available character set The following characters can be selected in text entry mode. The table is to be read across then down (eg, starting at space and repeatedly pressing NEXT gives ! “ # $ % & ‘ ( ) * etc.) “...
  • Page 123 PSM3750 user manual Appendix D – Configurable parameters All parameters can be accessed using the CONFIG command: CONFIG,parameter? CONFIG,parameter,data Number Function System parameters operating mode bandwidth auto or wide autozero manual or auto blanking disable phase convention main output on/off line drawing on/off keyboard beep on/off low frequency mode...
  • Page 124 PSM3750 user manual input ranging channel 2 coupling channel 1 coupling channel 2 scale factor channel 1 scale factor channel 2 external shunt channel 1 external shunt channel 2 input connection channel 1 input connection channel 2 General parameters 5/6 digit resolution phase reference output scaling output resolution...
  • Page 125 PSM3750 user manual PLC interface enable Power meter parameters integration type Streaming parameters data streaming data streaming window size Harmonic analyser parameters mode selected harmonic maximum harmonic computation LCR sweep zero parameters sweep compensation compensation start frequency compensation stop frequency compensation steps System parameters dBm level control...
  • Page 126 PSM3750 user manual LCR meter parameters invert nyquist nyquist origins computation series/parallel sweep graph option active head control impedance lin/log phase adjust value reference impedance reference type gain/phase analyser parameters phase or delay time selection dB offset gain/phase margin enable ratio selection System parameters minimum number of cycles...
  • Page 127 PSM3750 user manual Alarm functions alarm 2 data alarm 2 type alarm 2 high threshold alarm 2 low threshold Graph functions graph 2 manual/auto graph 2 maximum graph 2 minimum Phase angle voltmeter parameters computation LVDT scaling manual null meter ranging null maximum phase offset Trim parameters...
  • Page 128 Web site: www.newtons4th.com At Newtons4th Ltd. we have a policy of continuous product improvement and are always keen to hear comments, whether favourable or unfavourable, from users of our products. An example comment form can be found at the end of this manual –...
  • Page 130 PSM3750 NUMETRIQ comments serial main release: date: number: dsp release: fpga release: boot release: (press SYS then LEFT) your contact details: comments: detailed description of application or circumstances: Please post or fax to Newtons4th Ltd.

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