TENMA EX354RD & EX354RT Instruction Manual - Iss 1
Contents
1. 72 6855 amp 72 6856 BENCH POWER SUPPLIES INSTRUCTION MANUAL Tenma 72 6855 amp 72 6856 Instruction manual Table of Contents Introduction 2 Specification 2 Safety 4 Installation 5 Connections 5 Operation Main Outputs 6 Operation Auxiliary Output 7 Operation General 7 Maintenance 8 www tenma com 1 Introduction The 72 6855 and 72 6856 provide high levels of power up to 305 watts in a compact and attractive case style High resolution controls allow precise setting of voltage and current levels which are indicated on accurate and legible digital meters Excellent line and load regulation are matched by low noise and good transient response High power efficiency ensures that the unit remains cool without any fan noise Remote sense terminals are provided so that good regulation can be maintained across remote loads at high current The 72 6855 has two independent and isolated outputs each with a 0 to 35V 0 to 4A capability The outputs operate in constant voltage or constant current mode with automatic cross over and mode indication Each output has its own on off switch Where higher voltages or currents are required the outputs can be wired in either series or parallel to provide voltages up to 70 volts or currents up to 8 Amps The 72 6856 has in addition an Auxiliary logic voltage output with a 5A current capability To reflect the increasing usage of low voltage logic devices this output can be prese2. RH non condensing It may occasionally be subjected to temperatures between 5 C and 10 C without degradation of its safety Do not operate while condensation is present Use of this instrument in a manner not specified by these instructions may impair the safety protection provided Do not operate the instrument outside its rated supply voltages or environmental range WARNING THIS INSTRUMENT MUST BE EARTHED Any interruption of the mains earth conductor inside or outside the instrument will make the instrument dangerous Intentional interruption is prohibited The protective action must not be negated by the use of an extension cord without a protective conductor When the instrument is connected to its supply terminals may be live and opening the covers or removal of parts except those to which access can be gained by hand is likely to expose live parts The apparatus shall be disconnected from all voltage sources before it is opened for any adjustment replacement maintenance or repair Capacitors inside the power supply may still be charged even if the power supply has been disconnected from all voltage sources but will be safely discharged about 10 minutes after switching off power Any adjustment maintenance and repair of the opened instrument under voltage shall be avoided as far as possible and if inevitable shall be carried out only by a skilled person who is aware of the hazard involved If the instrument is clearly de
3. output terminals for such use On no account should the output terminals be touched when the unit is switched on under such use All connections to the terminals must be made with the power switched off on all units It should be noted that the unit can only source current and cannot sink it thus units cannot be series connected in anti phase The unit can be connected in parallel with others to produce higher currents Where several units are connected in parallel the output voltage will be equal to that of the unit with the highest output voltage setting until the current drawn exceeds its current limit setting upon which the output will fall to that of the next highest setting and so on In constant current mode units can be connected in parallel to provide a current equal to the sum of the current limit settings Ventilation The power supply is very efficient but nevertheless can generate significant heat at full power The supply relies on convection cooling only and it is therefore important that ventilation is never restricted if performance and safety are to be maintained www tenma com 7 Fuse Maintenance The Manufacturers or their agents overseas will provide repair for any unit developing a fault Where owner wish to undertake their own maintenance work this should only be done by skilled personnel in conjunction with the service manual which may be purchased directly from the Manufacturers or their agents overseas The
4. 5V to gt 5V by front panel control 0 3 4 digits 5A minimum Output will withstand up to 7V forward voltage Diode clamp reverse protection for currents up to 3A lt 0 5 for 90 load change lt 0 1 for 10 line voltage change Typically lt 2mVrms lt 10mVpk pk constant voltage mode Typically lt 200us to within 50mV of set level for a 5 to 95 load change Typically lt 100ppm C UNREG lamp 110V 240V AC 10 50 60HZ Installation Category Il 500VA max 5 C to 40 C 20 to 80 RH 40 C to 70 C Indoor use at altitudes up to 2000m Pollution Degree 2 Complies with EN61010 1 Complies with EN61326 260 x 160 x 320mm WxHxD 4 3kg www tenma com 3 Safety This power supply is a Safety Class instrument 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 This instrument has been tested in accordance with EN61010 1 and has been supplied in a safe condition This instruction manual contains some information and warnings which have to be followed by the user to ensure safe operation and to retain the instrument in a safe condition This instrument has been designed for indoor use in a Pollution Degree 2 environment in the temperature range 5 C to 40 C 20 80
5. correct fuse type is 10 Amp 250V HBC time lag T 5 x 20mm Note that the main function of the fuse is to make the instrument safe and limit damage in the event of failure of one of the switching devices If a fuse fails it is therefore very likely that the replacement will also blow because the supply has developed a fault in such circumstances the instrument will need to be returned to the manufacturer for service Make sure that only fuses of the required rated current and specified type are used for replacement The use of makeshift fuses and the short circuiting of fuse holders is prohibited To replace a fuse first disconnect the instrument from the AC supply Remove the 7 cover securing screws and lift off the cover Replace the fuse with one of the correct type and refit the cover Cleaning If the PSU requires cleaning use a cloth that is only lightly dampened with water or a mild detergent Polish the display window with a soft dry cloth WARNING TO AVOID ELECTRIC SHOCK OR DAMAGE TO THE PSU NEVER ALLOW WATER TO GET INSIDE THE CASE TO AVOID DAMAGE TO THE CASE OR DISPLAY WINDOW NEVER CLEAN WITH SOLVENTS TENMA TEST EQUIPMENT 405 Pioneer Blvd Springboro Ohio 45066 Book Part No 48511 1390 Issue 1
6. fective has been subject to mechanical damage excessive moisture or chemical corrosion the safety protection may be impaired and the apparatus should be withdrawn from use and returned for checking and repair Make sure that only fuses with the required rated current and of the specified type are used for replacement The use of makeshift fuses and the short circuiting of fuse holders is prohibited Do not wet the instrument when cleaning it The following symbols are used on the instrument and in this manual Earth ground terminal mains supply OFF mains supply ON alternating current ac 2 OF direct current dc Tenma 72 6855 amp 72 6856 Instruction manual Installation Mains Operating Voltage This instrument has a universal input range and will operate from a nominal 115V or 230V mains supply without adjustment Check that the local supply meets the AC Input requirement given in the Specification Mains Lead When a three core mains lead with bare ends is provided this should be connected as follows BROWN MAINS LIVE BLUE MAINS NEUTRAL L GREEN YELLOW EARTH Safety Earth Symbol When fitting a fused plug a 5 amp fuse should be fitted inside the plug As the colours of the wires in the mains lead of this apparatus may not correspond with the coloured markings identifying the terminals in your plug proceed as follows The wire which is coloured green and yellow must be connected to the terminal in the plu
7. g which is marked by the letter E or by the safety earth symbol shown above or coloured green or green and yellow The wire which is coloured blue must be connected to the terminal which is marked with the letter N or coloured black The wire which is coloured brown must be connected to the terminal which is marked with the letter L or coloured red WARNING THIS INSTRUMENT MUST BE EARTHED Any interruption of the mains earth conductor inside or outside the instrument will make the instrument dangerous Intentional interruption is prohibited Connections All connections are made from the front panel The load should be connected to the positive red and negative black terminals marked OUTPUT Remote sense connections to the load if required are made from the positive and negative SENSE terminals Switch the LOCAL REMOTE switch to REMOTE when remote sensing is required Switch back to LOCAL when remote sensing is not in use The terminal marked is connected to the chassis and safety earth ground www tenma com 5 Operation Main Outputs The operation of both main outputs is identical the following description applies to both Switching On The POWER switch is located at the bottom left of the front panel When the POWER switch is turned on I the right hand meter briefly indicates the firmware revision before the display shows Volts and Amps Setting Up the Output With the POWER switch on I and
8. protection and is protected from reverse voltages by a diode the continuous reverse current must not exceed 3 Amps although transients can be much higher The output is protected against externally applied forward voltages of up to 40V Remote Sensing The unit has a very low output impedance but this is inevitably increased by the resistance of the connecting leads At high currents this can result in significant differences between the indicated source voltage and the actual load voltage two 20mQ connecting leads will drop 0 2V at 5 Amps for instance This problem can be minimised by using short thick connecting leads but where necessary it can be completely overcome by using the remote sense facility This requires the sense terminals to be connected to the output at the load instead of at the source insert wires into the spring loaded SENSE terminals and connect directly to the load Switch the LOCAL REMOTE switch to REMOTE To avoid instability and transient response problems care must be taken to ensure good coupling between each output and sense lead This can be done either by twisting the leads together or by using coaxially screened cable sense through the inner An electrolytic capacitor directly across the load connection point may also be beneficial The voltage drop in each output lead must not exceed 0 5 Volts Switch the LOCAL REMOTE switch back to LOCAL when remote sensing is not in use Tenma 72 6855 amp 72 6856 In
9. struction manual Operation Auxiliary Output Output Voltage The output voltage can be set between 1 5V and 5 0V using the front panel rotary adjustment beside the centre terminals With the right hand main output OFF pressing the SHOW AUX PRESET button will display the AUX output voltage and current limit on the right hand meters Current Limit The output will go into current limit at between 5A and 6A the UNREG lamp lights in this condition Protection The output has intrinsic short circuit protection and is protected from reverse voltages by a diode the continuous reverse current must not exceed 3 Amps although transients can be much higher The output is protected against externally applied forward voltages of up to 7V Operation General Connection to the Load The load should be connected to the positive red and negative black output terminals Both are fully floating and either can be connected to ground Series or Parallel Connection with Other Outputs The outputs of the power supply are fully floating and may be used in series with other power supply units to generate high DC voltages up to 300V DC The maximum permissible voltage between any terminal and earth ground dy is 300VDC the maximum permissible voltage between either terminal of one output and any terminal of another output on the same supply is also 300VDC WARNING Such voltages are exceedingly hazardous and great care should be taken to shield the
10. t between 1 5 volts and 5 volts via a front panel control The total power capability is 280 watts for the dual supply and 305 watts for the triple The 72 6855 and 72 6856 incorporates separate digital voltage and current meters on each main output The meters use bright 14mm 0 56 LED displays and have an update rate of 4 per second providing near instantaneous response Simultaneous metering of voltage and current provides accurate information at a glance and avoids any possibility of misinterpretation When an output switch is set to off the current limit setting is displayed enabling conditions to be set before the load is connected With the right hand main output off the right hand meters can be used to momentarily display the preset Auxiliary voltage and current limit The 72 6855 and 72 6856 have been designed to meet the stringent requirements of relevant IEC standards for safety and EMC including harmonics emissions All outputs are intrinsically short circuit proof and are protected against external voltages and reverse currents MAIN OUTPUTS Voltage Range Current Range Output Voltage Setting Output Current Setting Operating Mode Output Switch Output Terminals Sensing Output Protection Load Regulation Line Regulation Specification OV to 35V minimum OA to 4A minimum By coarse and fine controls By single logarithmic control Constant voltage or constant current with automa
11. the sm output OFF the output voltage and current limit can be accurately preset using the VOLTAGE and CURRENT controls the left hand meter shows the set voltage and the right hand meter shows the set maximum current When the output switch is switched ON the ses lamp lights the left hand meter now shows the actual voltage and the right hand meter the actual load current Constant Voltage The output voltage is adjusted using the coarse and fine VOLTAGE controls the CURRENT control sets the maximum current that can be supplied Constant Current If the load resistance is low enough such that at the output voltage set a current greater than the current limit setting would flow the power supply will automatically move into constant current operation The current output is adjusted by the CURRENT control and the VOLTAGE controls set the maximum voltage that can be generated The CC lamp lights to show constant current mode Instantaneous Current Output The current limit control can be set to limit the continuous output current to levels down to 10mA However in common with all precision bench power supplies a capacitor is connected across the output to maintain stability and good transient response This capacitor charges to the output voltage and short circuiting of the output will produce a current pulse as the capacitor discharges which is independent of the current limit setting Protection The output has intrinsic short circuit
12. tic cross over Electronic Preset voltage and current displayed when off Universal 4mm safety binding posts on 19mm 0 75 pitch Switchable between local and remote Spring loaded push terminals for remote connection Output will withstand up to 40V forward voltage Reverse protection by diode clamp for reverse currents up to 3A lt 0 01 of maximum output for 90 load change using remote sense lt 0 01 of maximum output for 10 line change Ripple amp Noise 20MHz bandwidth Transient Response Temperature Coefficient Status Indication Meter Types Meter Resolutions Meter Accuracies Voltage Meter Voltage Accuracy Current Limit Output Protection Load Regulation Line Regulation Ripple amp Noise 20MHz bandwidth Transient Response Temperature Coefficient Status Indication GENERAL AC Input Power Consumption Operating Range Storage Range Environmental Safety EMC Size Weight Tenma 72 6855 amp 72 6856 Instruction manual Typically lt 2mVrms lt 10mVpk pk constant voltage mode lt 200us to within 50mV of set level for a 5 to 95 load change Typically lt 100ppm C Output on lamp Constant current mode lamp METER SPECIFICATIONS Main Outputs Dual 4 digit meters with 14mm 0 56 LEDs Reading rate 4 Hz 10mV 1mA Voltage 0 3 of reading 3 digits Current 0 5 of reading 3 digits AUXILIARY LOGIC OUTPUT 72 6855 only Variable lt 1
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