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Philips ure D.2 Channels connected in parallel to a load. Both channels are in Constant Volta, e mode.

Models: PM2811 PM2812 PM2813 PM2831 PM2832

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D - 2 Users Manual

This set-up will cause no problem as CH 1 supplies a constant current (CC) of 5A

and CH 2 supplies the additional current needed in constant volta

g

e mode (CV

indicator).

A problem will arise when the current needed by the load decreases below 5A, for

example when the load resistance increases. This is illustrated by fi

g

ure D.2.

Fi

g

ure D.2 Channels connected in parallel to a load. Both channels are in Constant Volta

g

e mode.

CH 1 will now enter the Constant Volta

g

e (CV) mode, as the current needed by

the load is less than Iset (5A). This implies that the volta

g

e across the load will

chan

g

e to the hi

g

hest Vset (12V). As Vset of CH 2 is 10V, its down pro

g

rammer

will become active, so that CH 1 will supply 3A plus the current the down

pro

g

rammer of CH 2 will sink. So this set-up is not suitable for load currents, which

can be lower than Iset of the Constant Current channel.

For this case there are two solutions. You can set the current of CH 1 to a value

below 3A so that CH 1 will enter the Constant Current mode as indicated in

Fi

g

ure D.1. Or, you can set both channels to the same volta

g

e, so that there will

be a constant volta

g

e across the load. When the volta

g

es are exactly equal, the

down pro

g

rammer will not become active and the current throu

g

h the load will be

equal to the sum of the currents of the individual channels.

Be careful in usin

g

the Standby and Disable modes

Consider the followin

g

case. You have connected two channels in parallel. You

don't need the second channel to supply current, because the first channel can

supply enou

g

h current. You disable the second channel to switch it off. The down

pro

g

rammer of this channel will try to sink its output to 0V. As the first channel still

supplies a volta

g

e, the down pro

g

rammer of the second channel will continuously

sink current. This causes power dissipation inside the case, which must be

prevented as the Power Supply is not desi

g

ned for this use.

Vset = 12V

Iset = 5A 4Ω

12V

3A

CC

3.5A

12V

CH1

Vset = 10V

Iset = 5A

CV

-0.5A

12V

CH2

Contents

Main PM2811-PM2812-PM2813 PM2831-PM2832 Users Manual Page Pro rammable Power Supplies III LIMITED WARRANTY & LIMITATION OF LIABILITY Page CONTENS 1 OPERATOR SAFETY 2 INTRODUCTION 3 INSTALLATION INSTRUCTIONS 4 GETTING FAMILIAR WITH THE POWER SUPPLY 5 USING YOUR PROGRAMMABLE POWER SUPPLY Page Page Page INSIDE THIS MANUAL Page 1 OPERATOR SAFETY 1.1 INTRODUCTION 1.2 SAFETY PRECAUTIONS 1.3 CAUTION AND WARNING STATEMENTS CAUTION: Is used to indicate correct operatin 1.4 SYMBOLS 1.5 IMPAIRED SAFETY 2 INTRODUCTION 2.1 INTRODUCTION TO YOUR PROGRAMMABLE POWER SUPPLY Page ! Single rear panel (PM2811 only) !!! -S -V +V +S -S -V +V +S READY START 2.2 BASIC OPERATION Page Page IEEE 488.2 compatibility SCPI compatibility Page Page Page Page 2.3 ADVANCED OPERATION Page Page 3 INSTALLATION INSTRUCTIONS 3.1 INTRODUCTION 3.2 INITIAL INSPECTION 3.3 OPERATOR SAFETY INSTRUCTIONS CAUTION: When an instrument is brou 3.4 INSTALLATION Page Note: Switchin Page Page 3.5 OUTPUT CONNECTIONS Page 3.6 ACCEPTANCE TESTS Page Note: For meanin es" in the Reference Manual. of the hardware error numbers, refer to section 3.6.1 "Brief check" or to "Error Messa Page 4 GETTING FAMILIAR WITH THE POWER SUPPLY 4.1 INITIAL SETUP OF YOUR POWER SUPPLY Normal self test indications Self test errors Note: The address aa is the actual GPIB device address (default = 28). Note: The SELECT function is applicable only for multiple output models. 4.2 FRONT PANEL LAYOUT . 4 - 4 Users Manual + Gettin Familair with the Power Supply 4 - 5 1) The CALIBRATION mode is entered when you turn on the power supply while pressin the AUX key. 2) To unlock the keyboard, press the ENTER key for approximately 5 seconds. Note: The output channel indication is displayed only for multiple output channel models. 4.3 OUTPUT CHANNEL CONNECTIONS 4.4 GETTING STARTED le output model the number n will not be displayed. Page Note: The diameter of the jumper wire must be lar e enou h to carry the maximum short-circuit current. Page Page 5 USING YOUR PROGRAMMABLE POWER SUPPLY 5.1 INTRODUCTION 5.2 LOCAL OPERATION = applies to multiple output models only. Note: 5.3 REMOTE OPERATION 5.4 OPERATING FEATURES Page CAUTION: Only output channels with equivalent volta e and current ratin ed. s may be connected in series or in parallel to prevent that the channel with the lowest ratin s will be dama 5.5 HOW TO USE THE OPERATING FEATURES PM2811/12/13 ure 5.5.1 Output Channel Characteristics PM2831/32 ure 5.5.2 Output channel characteristics ure 5.5.3 Current sink characteristics . any chan ure 5.5.4 Volta e drop due to Wire Resistance R mode: Remote sensin ure 5.5.6 Connection of a Load in the Remote Sense Mode mode: ure 5.5.5 Connection of a Load in the Local Sense Mode Page ure 5.5.7 Power Output Crossover Point Page Page Page Local control (in CV or CC mode): Remote control (in CV or CC mode): Page Note: To remember which locations have been pro rammed and which have not, keep a record (such as the followin ) of which locations have been used. Local control (store/recall): Remote control (store/recall): Manual step function: Remark: When the next step is executed, the next volta e and current settin ): Page Remote control (automatic steppin ): External step functions Note: LOW = 0 to 0.8V and HIGH = 2 to 5V Tri gg er bus control: nored. Note: STEP pulses, received while the READY line is low, will be i 5.6 ADVANCED USE Note: For the PM2812 and PM2813 you can face a number of restrictions when connectin output channels in parallel to a load. Please read Appendix D to (outputs in parallel): with Two Outputs in Parallel CAUTION: To prevent noise pickup, twist the sense wires and shield them from the environment. ure 5.6.1 Local Sensin Page Page Page Page DT+ DT Remote sensin (loads in parallel): CAUTION: To prevent noise pickup, twist the sense wires and shield them from the environment. ure 5.6.6 Remote Sensin withTwo Loads in Parallel APPENDIX A ACCESSORIES A.1 Supplied with the instrument A.2 Optional Page APPENDIX B SCPI CONFORMANCE INFORMATION Page Page B.3 SCPI approved B.4 SCPI syntax and style Page APPENDIX C ABBREVIATIONS, SYMBOLS & TERMS C.1 Abbreviations Page Page Page C.2 Glossary of symbols C.3 Glossary of terms Page Page APPENDIX D APPLICATION FOR PM2812 AND PM2813 e mode. ure D.2 Channels connected in parallel to a load. Both channels are in Constant Volta e mode. Note: Coupled Protection is possible only for the channels in the same Power Supply. Try to prevent that the down pro Case 1: Constant Current Case 2: Constant Volta e, Output Current from a fixed minimum value to the maximum Case 3: Constant Volta e, Output Current from 0A to the maximum Page INDEX A C D E F G I L M N O P R S T V W