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Aim-TTI LDH400P Instruction Manual

400w dc electronic loads
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LDH400P
400W DC Electronic Loads
INSTRUCTION MANUAL

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  • Page 1 LDH400P 400W DC Electronic Loads INSTRUCTION MANUAL...

  • Page 2: Table Of Contents

    Contents Introduction ....................4 Specification ....................5 Safety ......................9 Installation ....................10 Mains Operating Voltage ....................10 Mains Lead ........................10 Mounting ........................... 10 Ventilation ......................... 10 Fuses ..........................11 Connections ....................12 Front Panel Connections ....................12 Rear Panel Connections ....................12 Prospective Fault Current Protection ................
  • Page 3 11.6 Query Error Register - GPIB IEEE Std. 488.2 Error Handling ........... 41 11.7 Power on Settings ......................41 11.8 LDH400P Status Model ....................42 11.9 Register Summary ......................42 Remote Commands ..................44 12.1 Remote and Local Operation ..................44 12.2...
  • Page 4 Las instrucciones completas de funcionamiento y programación de este instrumento pueden encontrarse en la carpeta del producto correspondiente en el CD-ROM adjunto. También es posible descargar esta información desde la página de asistencia de la web de Aim-TTi, http://www.aimtti.com/support. Este manual es el 48511-1830 versión 2.

  • Page 5: Introduction

    1. Introduction This DC electronic load is for use in investigating the behaviour of many different types of high voltage DC power sources such as PFCs, batteries, solar cells, fuel cells or wind generators, as well as electronic power supply units. The load inputs are rated to CAT II (300V).

  • Page 6: Specification

    2. Specification Accuracy specifications apply for 18°C – 28ºC, using the rear panel terminals, after 30 minutes operation at the set conditions. Setting accuracies apply with slew rate at the ‘Default’ setting. INPUT Maximum Input Ratings Current: 16 Amps max. through the front and rear panel terminals. Voltage: 500 Volts max.
  • Page 7 Constant Conductance Mode (CG) Conductance Range: 0·001 to 1 A/V (1 mA/V resolution) Setting Accuracy: ± 0·5% ± 2 digits ± 30 mA (V > 25 Volts). Regulation: < 2% for 90% load power change (V > 25 Volts). Temperature Coefficient: <...
  • Page 8 Output Impedance: 600 nominal, for >1M load (e.g. oscilloscope) Scaling: 250mV per Amp (4 Volts full scale). Accuracy: ± 0·5% ± 5mV. Isolation: CATII (300V) to load negative. Bandwidth limit (-3dB): 40kHz. REMOTE CONTROL Digital Remote Interfaces The unit provides LAN, USB, GPIB (optional) and RS232 interfaces for full remote control. LAN: Ethernet 100/10base-T connection with auto cross-over detection.
  • Page 9 PROTECTION Excess Power: The unit will attempt to limit the power to 430 Watts; if this fails the unit will trip into the fault state at 460 Watts. Protection Current: The input is disabled if the measured current exceeds a user set limit. Excess Current: The unit will trip into the fault state at nominally 20 Amps.

  • Page 10: Safety

    3. Safety This instrument is Safety Class I according to IEC classification and has been designed to meet the requirements of EN61010−1 (Safety Requirements for Electrical Equipment for Measurement, Control and Laboratory Use). It is an Installation Category II instrument intended for operation from a normal single phase supply.

  • Page 11: Installation

    4. Installation 4.1 Mains Operating Voltage The operating voltage of the instrument is shown on the rear panel. Should it be necessary to change the operating voltage from 230V to 115V or vice-versa, proceed as follows: Disconnect the instrument from all voltage sources, including the mains and all inputs. Remove the screws which hold the case upper to the chassis and lift off.

  • Page 12: Fuses

    4.5 Fuses 4.5.1 Current Range Fuses The unit is protected by two 10A fuses that protect the unit against currents that exceed 20A. This is primarily as a protection against high power sources with a current capability of >20A being connected to the load with reverse polarity.

  • Page 13: Connections

    5. Connections 5.1 Front Panel Connections 5.1.1 Load Input The INPUT terminals for the load circuit on the front panel accept 4mm plugs. Their maximum current rating is 16 Amps. Do not use both the front panel and rear panel terminals simultaneously. The wiring and connection arrangement must be capable of supporting the current required.

  • Page 14: Prospective Fault Current Protection

    5.2.3 Digital Remote-Control Connections The LDH400P model provides full remote control capabilities through standard LAN, USB, GPIB (optional) and RS232 interfaces. All of these are isolated from the load input terminals of the unit. The USB, GPIB (optional) and RS232 interfaces are connected to chassis ground, and care must be taken to avoid introducing ground loops.

  • Page 15: Initial Operation

    Finally the digital remote control interfaces and command set of the LDH400P. 6.2 Load modes The power dissipating stage in this load is fundamentally an adjustable current sink, which conducts a current that does not depend on the voltage presently applied from the source being investigated.

  • Page 16: Voltage And Current Limit Conditions

    6.6 Voltage and Current Limit Conditions The unit has provision for the user to specify limits on the permitted measured value of voltage or current. If either of these limits is exceeded then the input will be disabled. 6.7 Power Limit The unit continuously monitors the internal power dissipation and varies the speed of the fan accordingly.

  • Page 17: Connecting The Load To The Source

    6.10 Connecting the Load to the Source The INPUT terminals of the load must be connected to the source to be tested using sufficiently low resistance and low inductance connections. Inductance in the interconnection can have a significant adverse impact on the stability of the source and load combination. The wiring should be as short and as thick as possible.

  • Page 18: Front Panel Operation

    7. Front Panel Operation In this manual, front panel labels are shown as they appear, in capitals, e.g. LEVEL SELECT Individual key names are shown in bold, e.g. Transient , and the blue soft-keys are referred to by their present function, as labelled on the bottom line of the display, shown in bold italics, e.g. Limits.

  • Page 19: The Display And The Home Screen

    7.2 The Display and the Home Screen All parameter settings and meter readings are shown on the backlit liquid crystal display (LCD). At power up the instrument initialises to the home screen, which is the normal display during operation of the unit. This screen displays all of the load meter readings and the most important load parameter settings as described below, and is also the top level of the soft-key driven menu structure.
  • Page 20 7.2.4 [D] Soft-Keys The soft-keys are the six blue keys found directly below the LCD. The function of each of these keys changes as the instrument is operated. The available function is shown on the bottom line of the display in a tab above each key. If any of the keys have no functionality in a particular menu then the tab is lowered to show it is inactive.

  • Page 21: General Numeric Entry Of Parameters

    7.3 General Numeric Entry of Parameters All user modifiable load parameters can be set using the numeric keypad. The desired parameter is first selected from the menu using the soft-keys. The display then changes to show the parameter entry screen which indicates the name of the parameter, its present value prior to editing, and in most cases the entry limits and resolution.

  • Page 22: Selection Of Load Mode

    Changing the load mode while the input is enabled will trip a fault detector and cause the input to be disabled before the change is implemented. 7.6 Selection of Load Mode The first action in configuring the unit for a particular application is to choose the load mode, which determines how the current drawn by the load varies with the applied voltage (V).

  • Page 23: Slow Start

    7.9 Slow Start The purpose of the slow start circuit is to ramp the demand of the load up slowly from zero to the final value. The rate of rise is determined by the Slew Rate setting. The ramp starts either when the Input is Enabled, or when the voltage from the attached source passes the level of the Dropout Voltage setting.

  • Page 24: Transient Frequency

    7.12 Transient Frequency The repetition rate of the internally timed transients can be set in terms of frequency or period. Pressing the Freq or Period soft-key on the Transient menu opens the Frequency and Period setting menu. A new value can be entered, in the present representation, in the usual manner. Two soft-keys labelled Freq and Period allow the alternative representation to be chosen.

  • Page 25: Voltage And Current Limits

    The bandwidth of the power stages of the load is reduced (by changing the compensation networks) when the slew rate is set to less than 0·1% of the maximum slew rate for the given load mode. For example, in constant current mode, the maximum slew rate setting is 500A/ms, so the bandwidth is reduced when the slew rate is set <...

  • Page 26: Store And Recall Facilities

    7.16 Store and Recall Facilities The instrument is able to store and recall up to 30 user defined sets of load parameters in non-volatile memory. Each memory location holds all the parameter settings – load Mode, active level, Level A value, Level B value, Dropout Voltage level, transient Frequency, Duty and Slew Rate and the state of Slow start.

  • Page 27: Utilities Menu

    7.17 Utilities Menu Pressing the Utilities soft-key on the home screen gives access to four sub-menus to configure various instrument settings and preferences. Instruments fitted with Digital Remote Control interfaces have a fifth sub-menu. The selection can be made using either the ▲ or ▼ soft-keys or the knob.

  • Page 28: Analogue Remote Control

    8. Analogue Remote Control Two forms of voltage controlled remote operation are available: External Voltage Control, where an analogue voltage fully defines the demanded level of the chosen operating mode, and External TTL Control where an external logic voltage selects between the two levels set as Level A and Level B.

  • Page 29: Application Notes

    9. Application Notes This chapter is intended to give helpful information concerning practical applications of the unit. All electronic loads are subject to the impact of source characteristics, interconnection inductance and feedback loop characteristics, which can give rise to unexpected instability or poor dynamic behaviour.

  • Page 30: Stability Of Source And Load Combinations

    9.2 Stability of Source and Load Combinations This instrument is optimised for accuracy under constant load conditions by using a high gain feedback loop. Because of this, the possibility exists for combinations of source, interconnection and load characteristics to give rise to instability. There are three major potential causes: inductance in the wiring between source and load (or an inductive output impedance of the source), capacitance in parallel with the connection between source and load (including an output capacitor within the source) and the characteristics of active feedback circuits within the source.

  • Page 31: Start-Up Transients

    9.3.1 Source Characteristics The purpose of transient testing is to examine the behaviour of any feedback loops within the source. If the response of the source is under-damped, then in general the use of an active load will accentuate the effect. This is particularly true in the modes where the load responds to changes in voltage.
  • Page 32 9.5.1 Constant Current Mode As described above, this is the fundamental operating mode of the power stages of this instrument, so it has the simplest feedback loop and the widest bandwidth. The sensed voltage signal is only used for the meters and protection. Constant current mode is normally used in conjunction with low impedance power supplies, and will be quite stable unless there is significant inductance in either the interconnections or the source.

  • Page 33: Multiple Unit Operation

    sensed voltage by the specified conductance; in Resistance mode the current required is calculated by dividing the difference between the sensed voltage and the dropout voltage setting by the specified resistance. In both cases, the current rises as the applied voltage rises. At equivalent resistance and conductance settings, the path from the voltage sense input through to the power stage is the same, so the two modes will exhibit similar stability characteristics.

  • Page 34: Remote Interface Configuration

    10. Remote Interface Configuration The LDH400P model can be remotely controlled via its RS232, USB, GPIB (optional) or LAN interfaces. The GPIB interface (optional) provides full facilities as described in IEEE Std. 488 parts 1 and 2. The RS232 interface communicates directly with a standard COM port.

  • Page 35: Usb Interface And Device Driver Installation

    The Baud Rate for this instrument is fixed at 9600; the other parameters are 8 data bits, no parity and one stop bit. Flow control uses the XON/XOFF protocol, but because of the low volume of data associated with this instrument it is very unlikely that flow control will actually be invoked. 10.3 USB Interface and Device Driver Installation The instrument firmware can be updated in the field through the USB port.
  • Page 36 Since it is possible to misconfigure the LAN interface, making it impossible to communicate with the instrument over LAN, a LAN Configuration Initialise (LCI) mechanism is provided via a push switch (marked LAN reset) accessible through a small hole in the rear panel. This restores the default configuration with DHCP enabled, so the unit will then follow the sequence described in the previous paragraph.

  • Page 37: Interface Locking

    display the Home page of that device. For a later version of the tool that supports discovery by both VXI-11 and mDNS visit www.lxistandard.org . There are also tools for LAN discovery included as part of the National Instruments Measurement and Automation Explorer package and the Keysight Vee application.
  • Page 38 Note: it is also possible to configure the privileges for a particular interface to either ‘read only’ or ‘no access’ from the Web page interface.

  • Page 39: Status Reporting

    11. Status Reporting The standard status and error reporting model described in IEEE Std. 488.2 was designed for the GPIB interface (optional) and contains some features intended for use with the Service Request and Parallel Poll hardware capabilities of that interface, and to accommodate its semi-duplex operation.

  • Page 40: Standard Event Status Registers (Esr And Ese)

    The Input Trip Enable Register provides the mask between the Input Trip Register and the Status Byte Register. If any bit becomes ‘1’ in both registers, then the INTR bit (bit 1) will be set in the Status Byte Register. This enable register is set by the ITE command to a value 0 - 255, <NRF>...

  • Page 41: Execution Error Register (Eer)

    The Standard Event Status Enable Register provides a mask between the Event Status Register and the Status Byte Register. If any bit becomes ‘1’ in both registers, then the ESB bit will be set in the Status Byte Register. This enable register is set by the *ESE command to a value <NRF>...

  • Page 42: Gpib (Optional) Parallel Poll (Pre)

    11.5 GPIB (optional) Parallel Poll (PRE) Complete Parallel Poll capabilities are offered by this instrument as defined in IEEE Std. 488.1. The Parallel Poll Enable Register (which is set by the *PRE command and read by the <NRF> *PRE? query) specifies which bits in the Status Byte Register are to be used to form the ist local message.

  • Page 43: Ldh400P Status Model

    11.8 LDH400P Status Model 11.9 Register Summary Query Name † ITR? Input Trip Register...
  • Page 44 *SRE *SRE? Status Byte Enable Register *PRE *PRE? Parallel Poll Response Enable Register † These registers are cleared after being queried, or by the *CLS command.

  • Page 45: Remote Commands

    12. Remote Commands 12.1 Remote and Local Operation At power-on the instrument will be in the local state, with normal keyboard operation possible. All remote interfaces are active and listening for a remote command. When any command is received from any interface the instrument will enter the remote state. In this state the keyboard is locked out, the display switches to the home screen, with R E M O T E displayed in place of the soft-key tabs.

  • Page 46: Command Timing

    12.4 Command Timing There are no dependent parameters, coupled parameters, overlapping commands, expression program data elements or compound command program headers. Note, however, that the MODE command sets standard values for Level A, Level B, Range and the Slew Rate, so these must be explicitly set afterwards.
  • Page 47 Set Level A to . The units are implied by the present load mode. <NRF> <NRF> Set Level B to . The units are implied by the present load mode. <NRF> <NRF> Return the set Level of Level A. The response is: A <NR2>...
  • Page 48 Returns the measured source input voltage. The response is where is in Volts. <NR2> <RMT> <NR2> Returns the measured load current The response is where is in Amps. <NR2> <RMT> <NR2> 12.6.2 Common Commands *IDN? Returns the instrument identification. The response is in the form <NAME>, <model>, <serial>, <version> <RMT>...
  • Page 49 *SRE Sets the Service Request Enable Register to <NRF> <NRF> *SRE? Report the value in the Service Request Enable Register. The response is <NR1><RMT> *PRE Set the Parallel Poll Enable Register to the value <NRF> <NRF> *PRE? Report the value in the Parallel Poll Enable Register. The response is <NR1><RMT>...

  • Page 50: Maintenance

    13. Maintenance The Manufacturers or their agents overseas will provide a repair service for any unit developing a fault. Where owners wish to undertake their own maintenance work, this should only be done by skilled personnel in conjunction with the Service Guide, which may be obtained directly from the Manufacturers or their agents overseas.

  • Page 51: Sécurité

    14. Sécurité Cet instrument est conforme à la classe de sécurité 1 de la classification CEI et il a été conçu pour satisfaire aux exigences de la norme EN61010-1 (Exigences de sécurité pour les équipements électriques de mesure, de contrôle et d'utilisation en laboratoire). Il s'agit d'un instrument de catégorie II d'installation prévu pour un fonctionnement à...

  • Page 52: Sicherheit

    15. Sicherheit Dieses Gerät wurde nach der Sicherheitsklasse (Schutzart) I der IEC-Klassifikation und gemäß den europäischen Vorschriften EN61010-1 (Sicherheitsvorschriften für elektrische Mess-, Steue-, Regel- und Laboranlagen) entwickelt. Es handelt sich um ein Gerät der Installationskategorie II, das für den Betrieb von einer normalen einphasigen Versorgung vorgesehen ist. Das Gerät wurde gemäß...

  • Page 53: Sicurezza

    16. Sicurezza Questo strumento appartiene alla Categoria di Sicurezza 1 secondo la classifica IEC ed è stato progettato in modo da soddisfare i criteri EN61010-1 (requisiti di Sicurezza per Apparecchiature di misura, controllo e per uso in laboratorio). E’ uno strumento di Categoria II di installazione e inteso per funzionamento con un’alimentazione normale monofase.
  • Page 54 17. Seguridad Este es un instrumento de Clase Seguridad I según la clasificación del IEC y ha sido diseñado para cumplir con los requisitos del EN61010-1 (Requisitos de Seguridad para Equipos Eléctricos para la Medición, Control y Uso en Laboratorio). Es un equipo de Categoría de Instalación II que debe ser usado con suministro monofásico normal.
  • Page 56 Book Part No. 48511-1830 Issue 2...

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