Aim-TTI LD400 Instruction Manual
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Aim-TTI LD400 Instruction Manual

400w dc electronic loads
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LD400 & LD400P
400W DC Electronic Loads
INSTRUCTION MANUAL

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Summary of Contents for Aim-TTI LD400

  • Page 1 LD400 & LD400P 400W DC Electronic Loads INSTRUCTION MANUAL...

  • Page 2: Table Of Contents

    Table of Contents Specification Safety Installation Connections Initial Operation Organisation of this manual Connecting the Load to the Source Switching On Front Panel Operation Keys and ∆ Adjust The Display and the Home Screen General Numeric Entry of Parameters Variation of Parameter Values using ∆ Adjust Configuring the Load Selection of Load Mode Level A and Level B Setting and Range Selection...
  • Page 3 Full operating and programming instructions for this instrument can be found in the appropriate product folder of the accompanying CD-ROM. This information can also be downloaded from the support page of the Aim-TTi website. This manual is 48511-1730 Issue 2.
  • Page 4 Introduction This DC electronic load is intended for use in investigating the behaviour of many different types of DC power sources such as batteries, solar cells, fuel cells or wind generators, as well as electronic power supply units. It is designed to have very low internal resistance to allow operation at high currents with low voltage drop.

  • Page 5: Specification

    Specification Accuracy specifications apply for 18°C – 28ºC, using the rear panel terminals, at 50W load power (in normal 400W mode), after 30 minutes operation at the set conditions; regulation specifies variation at other powers. Setting accuracies apply with slew rate at the ‘Default’ setting. Superscript references are to footnotes on page 7, which provide further clarification.
  • Page 6 Constant Resistance Mode (CR) 0·04 to 10 Ω (0·01 Ω resolution) and 2 to 400 Ω (0·1 Ω resolution). Resistance Ranges: Setting Accuracy: ±0·5% ± 2 digits ± 30 mA. Regulation: < 2% for 90% load power change (V > 2 Volts, using remote sense). Temperature Coefficient: <...
  • Page 7 DROPOUT VOLTAGE The load will cease to conduct if the applied voltage falls below the Dropout Voltage setting; active in all modes except Constant Voltage. The Dropout Voltage setting is also the threshold for the Slow Start facility and acts as an offset voltage in Constant Resistance mode. Setting Accuracy: ±...
  • Page 8 Remote Disable Input Connection: Terminal block on rear panel. Input to the LED of an opto-isolator through 1kΩ resistor. Threshold: Apply >+3V to disable the load input. Max. Voltage 12V. PROTECTION Excess Power: The unit will attempt to limit the power to approx 430 Watts; if this fails the unit will trip into the fault state at about 460 Watts.
  • Page 9 Cambridgeshire PE29 7DR England declare that the LD400 and LD400P DC Electronic Loads Meet the intent of the EMC Directive 2004/108/EC and the Low Voltage Directive 2006/95/EC. Compliance was demonstrated by conformance to the following specifications which have been listed in the Official Journal of the European Communities.

  • Page 10: Emc

    This instrument has been designed to meet the requirements of the EMC Directive 2004/108/EC. Compliance was demonstrated by meeting the test limits of the following standards: Emissions EN61326-1 (2013) EMC product standard for Electrical Equipment for Measurement, Control and Laboratory Use. Test limits used were: Radiated: Class B...

  • Page 11: Safety

    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 12: Installation

    Installation 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 13: Connections

    Connections Front Panel Connections Load Input The INPUT terminals for the load circuit on the front panel accept 4mm plugs into the end, 2mm diameter wire into the cross hole, or ¼ inch spade connections. Their maximum current rating is 30 Amps.
  • Page 14 Terminal Blocks All other rear panel connections are made via the screw-less terminal blocks. To make connections to the terminal blocks, use a flat screwdriver to press the spring-loaded orange actuator inwards to open the wire clamp; insert the wire end fully into the hole and release the actuator.

  • Page 15: Initial Operation

    Initial Operation This instrument provides a controllable DC load (a power sink) intended for testing all forms of DC power supply including batteries, photo-voltaic cells, fuel cells, turbines and generators as well as electronic power supply units. Organisation of this manual The paragraphs below are intended to briefly introduce the particular features of this instrument and the terminology used in this manual.
  • Page 16 Short Term Operation up to 600 Watts The instrument has provision for applications which require the dissipation of higher than normal powers for a limited period of time. It imposes a limit on the combination of power and time by first displaying a warning message and then disabling the input.

  • Page 17: Connecting The Load To The Source

    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

    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. Recall.
  • Page 19 Home Screen Data Below the status line are the meter displays which show the actual measured source voltage and, once the load is enabled, the load current. Below this, the screen is divided into three areas. On the left, under the heading METERS, the display shows the present power in the load and the equivalent resistance;...

  • Page 20: General Numeric Entry Of Parameters

    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 21: Selection Of Load Mode

    input is enabled. Changing either the load mode or the level range while the input is enabled will trip a fault detector and cause the input to be disabled before the change is implemented. 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 22: Slow Start

    a soft entry into the dropout condition – the series voltage drop will reduce as the current starts to fall, so raising the voltage measured by the load. Batteries may also recover as the load is reduced, raising the voltage back above the dropout threshold so the load resumes conduction. There is a possibility of hunting or instability in this operating condition.

  • Page 23: Transient Menu

    Enabled, or when the Transient level control key is selected, or (if the slow start circuit is active) when the source voltage rises above the Dropout Voltage threshold. It is also possible to use the External Analogue Voltage control mode to generate transients of any required shape by using an external generator to produce the required waveform.
  • Page 24 millisecond or (at very slow rates) Watts per second. The shape of the current transition is therefore not necessarily linear in any mode other than Constant Current (CC). In addition to the usual numeric prompt this menu also shows the calculated theoretical transition time considering the present Slew Rate setting and the difference between Level A and Level B.

  • Page 25: Voltage And Current Limits

    Voltage and Current Limits These limits specify values of source voltage and load current which will cause the load to automatically disable its input if the actual measured voltage or current exceeds the set limit. This is not an independent hardware trip, but a simple comparison against the meter measurements. To access the Limits menu, press the Limits soft-key on the home screen.

  • Page 26: Store And Recall Facilities

    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, the state of Slow start and the state of the 600 Watt option.

  • Page 27: Utilities Menu

    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

    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

    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

    Shunt capacitance The load can only sink current, so it can only pull the voltage at its terminals down. The source must pull the voltage up, including providing charging current to any capacitance across the terminals. If the total current available is more than sufficient to charge this capacitance at the slew rate required, then the load will continue to conduct the excess current during the transition and the behaviour will be as expected.

  • Page 31: Start-Up Transients

    Because of changes in the transconductance of the FETs, the dynamic behaviour of the power stages changes at both low and high currents, and also at low voltages when the inter-electrode capacitance increases considerably. In general, behaviour is optimum in the middle of the current range (5 to 60 Amps) and at voltages between about 3 volts and (if there is significant source impedance) about 3 volts below the open circuit voltage of the source.
  • Page 32 both the gain and the inter-electrode capacitance of the FETs vary with operating point, particularly at low voltages (below about 3V) and at either low or high currents. This results in slower response and different stability conditions and dynamic behaviour in these regions, whatever the operating mode.
  • Page 33 In transient operation, if the source is constant voltage (with low source impedance), then the current will follow the changes in power demand and the response will be very similar to constant current mode. If the source voltage falls as the power demand increases, then (as described above) the current has to increase more than proportionally and the current slew rate rises;...

  • Page 34: Multiple Unit Operation

    in turn results in a transient increase in the output voltage of the supply, and then the process repeats. This type of instability can be recognised by the characteristic short pulses of current separated by longer periods of zero current. Sometimes this instability can be avoided by setting the load threshold well below the open circuit output voltage of the source.

  • Page 35: Remote Interface Configuration

    Remote Interface Configuration The LD400P model can be remotely controlled via its RS232, USB, GPIB or LAN interfaces. The GPIB interface provides full facilities as described in IEEE Std. 488 parts 1 and 2. The RS232 interface communicates directly with a standard COM port. The USB interface enumerates as a Communications Class device and interacts with application software through a standard virtual COM port device driver on the PC.

  • Page 36: Usb Interface And Device Driver Installation

    USB Interface and Device Driver Installation The instrument firmware can be updated in the field through the USB port. This does not need the driver described here. It requires a PC software utility provided by the manufacturer, and uses a HID driver that will already be installed on the PC. If that is the only USB functionality required, download the package containing the firmware update together with the PC utility from the manufacturer, and follow the instructions included.
  • Page 37 default configuration with DHCP enabled, so the unit will then follow the sequence described in the previous paragraph. Note that resetting the LAN interface removes any password protection. The progress of establishing a LAN connection can be viewed either by inspecting the Interface Settings menu (from the home screen press Utilities then Interface Settings) or by interpreting the symbol shown on the status line of the home screen, which has four possible indications: No LAN...
  • Page 38 included as part of the National Instruments Measurement and Automation Explorer package and the Agilent Vee application. VXI-11 Discovery Protocol The instrument has very limited support of VXI-11 which is sufficient for the discovery protocol and no more. It implements a Sun RPC Port-mapper on TCP port 111 and UDP port 111 as defined in RFC1183.

  • Page 39: Status Reporting

    Status Reporting The standard status and error reporting model described in IEEE Std. 488.2 was designed for the GPIB interface 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 that no longer apply will be cleared; any bit reporting a condition that remains true will remain set. 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.
  • Page 41 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 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 LD400 Status Model EXECUTION ERROR QUERY ERROR FAULT TRIP 600W DURATION TRIP NUMBER NUMBER OVER VOLTAGE TRIP EER? QER? OVER CURRENT TRIP TRIP POWER COMMAND OPERATION ITR? ERROR COMPLETE & & & & *ESR? & & & & & INPUT DISABLED...

  • Page 44: Remote Commands

    Remote Commands 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 45 MODE command sets standard values for Level A, Level B, Range and the Slew Rate, so these must be explicitly set afterwards. Alternatively it is possible to use the store and recall facilities of the instrument to quickly retrieve a complete set-up of an operating mode and its values. All commands are separate and sequential, and are executed when parsed and immediately considered complete.
  • Page 46 600W Set 600W mode on or off, where has the meaning: <NRF> <NRF> 0=Off (400W mode), 1=On (600W mode). 600W? Returns the setting of the 600W mode. The response is: 600W where is either 0 or 1, where <NR1><RMT> <NR1> 0=400W mode or 1=600W mode.
  • Page 47 Set the input on or off where has the meaning: 0=Off, 1=On. <NRF> <NRF> INP? Returns the input state. The response is INP where is either 0 (=Off) or 1 (= On). <NR1><RMT> <NR1> Returns the measured source input voltage. The response is where is in Volts.
  • Page 48 QER? Query and clear Query Error Register. The response format is <NR1><RMT> *STB? Report the value of the Status Byte. The response is: <NR1><RMT> Because there is no output queue, MAV can only be read by a GPIB serial poll, not by this query, as any previous message must have already been sent.

  • Page 49: Maintenance

    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 50 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 51 Sicherheit Dieses Gerät wurde nach der Sicherheitsklasse (Schutzart) I der IEC-Klassifikation und gemäß den europäischen Vorschriften EN61010−1 (Sicherheitsvorschriften für elektrische Mess-, Steuer-, Regel- und Laboranlagen) entwickelt. Es handelt sich um ein Gerät der Installationskategorie II, das für den Betrieb mit einer normalen einphasigen Versorgung vorgesehen ist.
  • Page 52 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). È uno strumento di Categoria II di installazione e inteso per funzionamento con un’alimentazione normale monofase.
  • Page 53 Seguridad El presente instrumento pertenece a la Clase de Seguridad I de la clasificación CEI y ha sido diseñado para cumplir las prescripciones de la norma EN61010-1 (Requisitos de seguridad de equipos eléctricos de medida, control y uso en laboratorio). Se trata de un instrumento de la Categoría de Instalación II que se debe alimentar con una fuente monofásica normal.
  • Page 54 Book Part No. 48511-1730 Issue 2...

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