TTI QPX600D User manual

QPX600D & QPX600DP
PowerFlex+ Dual DC Power Supplies
INSTRUCTIONMANUAL

1
Table of Contents
Specification 2
EMC 6
Safety 7
Installation 8
Connections 9
Initial Operation 11
Manual Operation – Independent Mode 13
Manual Operation – Link Modes 21
Maintenance 22
Remote Operation 23
Remote Commands (QPX600DP only) 32
Note: The latest revisions of this manual, device drivers and software tools can be
downloaded from: http://www.tti-test.com/go/qsx
This manual is 48511-1460 Issue 7

2
Specification
General specifications apply for the temperature range 5°C to 40°C. Accuracy specifications
apply for the temperature range 18°C to 28°C after 1 hour warm-up with no load and calibration at
23°C. Typical specifications are determined by design and are not guaranteed.
OUTPUT SPECIFICATIONS (Each Output)
Voltage Range: Two ranges: 0V to 60V or 0V to 80V
Current Range: 0.01A to 50A
Power Range: Up to 600W
Voltage Setting: Resolution: 1mV (60V Range),
2mV (80V Range)
Accuracy: 0.1% of setting ± 2mV,
(± 4mV on 80V range)
Current Setting: Resolution 10mA
Accuracy: 0.3% of setting ± 20mA
Operating Mode: Constant voltage or constant current
with automatic cross-over provided
that the power demanded stays within
the power envelope, see graph.
Outside of this envelope the output
becomes unregulated. CV, CI or
UNREG mode indication in display.
Output Switch: Independent electronic switching, with ON indication. In addition, BOTH ON
and BOTH OFF keys permit both outputs to be switched on/off
synchronously (±10µs). Preset voltage and current displayed when off.
Output Terminals: Rear panel safety terminals accepting 6mm wire diameter, 6mm plugs or
8mm spades at 50 Amps max, or 4mm plugs at 30 Amps max.
Sensing: Switchable between local and remote. Screwless remote sense terminals on
rear panel. Sense miswiring trip and indication.
Ripple & Noise
(20MHz bandwidth): Typically <3mVrms, <20mV pk-pk at maximum load, CV mode
Load Regulation: Change in output for any load change within PowerFlex envelope, using
remote sense:
Constant voltage: <0.01% ± 5mV
Line Regulation: Change in output for a 10% line change:
Constant voltage: <0.01% ± 5mV
Transient Response: <2ms to within 100mV of set level for a 5% to 95% load change.
Output Protection: Output will withstand an applied forward voltage of up to 90V.
Reverse protection by diode clamp for reverse currents up to 3A.
Over-voltage Protection
(OVP): Range 2V to 90V. Resolution 0.1V; accuracy: 0.2% ± 0.2V.
Response time typically 100µs.
Over-current Protection
(OCP): Range 2A to 55A. Resolution 0.1A; accuracy: 0.5% ± 0.2A. Response time typically 100ms.
Over-temperature
Protection: The output will be tripped off if a fault causes the internal temperature to rise excessively.
Temperature Coefficient: Typically <100ppm/°C
QPX600D & DP
Power Envelope
(per channel)

3
METER SPECIFICATIONS (Each Output)
Display Type: 5-digit (Volts), 4-digit (Amps), black-on-white backlit LCD.
Voltage
(CI Mode and Unreg): Resolution 1mV Accuracy: 0.1% of reading ± 2 digits
Current
(CV Mode and Unreg): Resolution 10mA Accuracy: 0.3% of reading ± 2 digits
V x A: Resolution 0·1W
Accuracy: 0·5% ± 0·1W
V/A: Meter shows calculated nominal V/A value, together with uncertainty
range; 5 digit resolution.
LOGIC CONTROL INPUT and OUTPUT (Each Output)
LOGIC IN is a rear-panel opto-isolated input that is activated at an input current greater than
approximately 1mA. User can set LOGIC IN (via the keyboard) to enable the output, disable the
output, or be ignored when it is activated.
LOGIC OUT is an isolated rear-panel open-collector output that will sink up to 2mA when activated
(‘switch closure’); the maximum voltage that can be applied to LOGIC OUT is 30VDC. User can
set LOGIC OUT to be ‘closed’ or ‘open’ for output enabled or disabled, current limit
(CI mode), power limit (UNREG mode), or for any fault trip.
ANALOG REMOTE CONTROL and MONITORING (Each Output)
Quasi-analogue inputs and outputs to set voltage and current limit and to monitor actual output
voltage and current. The control inputs are read four times per second by the
A-D converter and the output is set according to the selected input scaling; similarly the monitor
outputs are updated four times per second with values representing the actual output voltage and
current. These signals each have a range of 0 to 10V or 0 to 5V with respect to the shared COM
return signal; the set range applies to all inputs and outputs.
Analogue Control Voltage Range: Keyboard selectable to be 0 to 10Vdc or 0 to 5Vdc for
range maximum output. Absolute maximum input 20Vdc.
Analogue Control Accuracy: Voltage: 0.3% ± 4mV; Current: 0.5% ± 40mA.
Analogue Control Common Mode Range: ± 2.5Vdc max to negative output.
Analogue Control Input Impedance: Nominally 40kΩ.
Analogue Monitor Voltage Range: Same as set for Analogue Control Voltage Range.
Analogue Monitor Accuracy: Voltage: 0.3% ± 4mV; Current: 0.5% ± 40mA.
Analogue Monitor Output: Connect to isolated measuring system with >10kΩinput
impedance. Will withstand a short-circuit.
LINK MODES
In addition to independent output operation, the instrument is capable of operating in a number of
different voltage tracking modes which can be activated from the LINK MENU. These modes
include Output 2 voltage (V2) tracking Output 1 voltage (V1) by any ratio in the range 5% to
2000%, V2 and I2 set to track V1 and I1 (1:1) with total V1 + V2 displayed (useful when Output 1
and Output 2 are series connected), V2 and I2 set to track V1 and I1 (1:1) with total I1 + I2
displayed (useful when Output 1 and Output 2 are parallel connected).
KEYBOARD & ROTARY CONTROL
All functions, including the selection and set-up of the remote control interfaces, can be set from
the keyboard. The rotary Jog control can be used to adjust output voltage and current settings in a
quasi-analogue mode. The output to be controlled is first selected with the appropriate Control key.

4
DISPLAY FEATURES
The displays (one for each output) are graphic LCDs, backlit by white LEDs; contrast is software-
controlled and can be adjusted from the keyboard.
The default status displays show the VOLTS (5 digits) and AMPS (4 digits) in 12mm high
characters, plus output range and status. At other times, for example during store or recall of
instrument set-ups, the displays show up to 7 lines of information, instructions, or prompts.
INTERFACES (QPX600DP only)
Full digital remote control facilities are available through the RS232, LAN, USB and GPIB
interfaces. Setting and readback resolutions are the same as for the Output and Meter
specifications respectively.
RS232: Standard 9-pin D-connector. Baud rate 9600.
USB: Standard USB 2.0 hardware connection.
LAN: Auto speed detect(10/100MHz), Auto MDIX.
LXI V1.2, Class C compliant.
GPIB: Conforms with IEEE488.1 and IEEE488.2.
Remote Command
Processing Time: Typically <100ms between receiving the command terminator for a step voltage change at the instrument and the output voltage
beginning to change.
GENERAL
AC Input: 115V – 240V AC ± 10%, 50/60Hz.
Installation Category II.
Power Consumption: 1600VA max.
Operating Range: +5ºC to +40ºC, 20% to 80% RH.
Storage Range: −40ºC to + 70ºC.
Environmental: Indoor use at altitudes up to 2000m, Pollution Degree 2.
Store/Recall: Up to 10 set-ups can be saved and recalled via the keyboard or
remote interfaces.
Safety: Complies with EN61010-1.
EMC: Complies with EN61326.
Size: 130mm H (3U) x 356mm W x 413mm D
Weight: 9.2kg
Options: 19-inch rack kit.

5
EC Declaration of Conformity
We Thurlby Thandar Instruments Ltd
Glebe Road
Huntingdon
Cambridgeshire PE29 7DR
England
declare that the
QPX600DP & QPX600D Power Supplies
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.
EMC
Emissions: a) EN61326-1 (2006) Radiated, Class A
b) EN61326-1 (2006) Conducted, Class A
c) EN61326-1 (2006) Harmonics, referring to EN61000-3-2 (2006)
Immunity: EN61326-1 (2006) Immunity Table 1, referring to:
a) EN61000-4-2 (2009) Electrostatic Discharge
b) EN61000-4-3 (2006) Electromagnetic Field
c) EN61000-4-11 (2004) Voltage Interrupt
d) EN61000-4-4 (2004) Fast Transient
e) EN61000-4-5 (2006) Surge
f) EN61000-4-6 (2009) Conducted RF
Performance levels achieved are detailed in the user manual.
Safety
EN61010-1 Installation Category II, Pollution Degree 2.
CHRIS WILDING
TECHNICAL DIRECTOR
2 January 2013

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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 (2006) EMC product standard for Electrical Equipment for Measurement, Control and
Laboratory Use. Test limits used were:
a) Radiated: Class A
b) Conducted: Class A
c) Harmonics: EN61000-3-2 (2006) Class A; the instrument is Class A by product category.
Immunity
EN61326-1 (2006) EMC product standard for Electrical Equipment for Measurement, Control and
Laboratory Use.
Test methods, limits and performance achieved are shown below (requirement shown in brackets):
a) EN61000-4-2 (2009) Electrostatic Discharge: 4kV air, 4kV contact, Performance A (B).
b) EN61000-4-3 (2006) Electromagnetic Field:
3V/m, 80% AM at 1kHz, 80MHz – 1GHz: Performance B*(A) and
1.4GHz to 2GHz: Performance A (A); 1V/m, 2.0GHz to 2.7GHz: Performance A (A).
c) EN61000-4-11 (2004) Voltage Interrupt: ½ cycle and 1 cycle, 0%: Performance A (B);
25 cycles, 70%: Performance A (C); 250 cycles, 0%: Performance B (C), if Function 11 is
set (Output status at power-up same as at last power-down), otherwise Performance C.
d) EN61000-4-4 (2004) Fast Transient, 1kV peak (AC line only; DC Output connections <3m,
therefore not tested†), Performance B (B).
e) EN61000-4-5 (2006) Surge, 0·5kV (line to line), 1kV (line to ground), Performance B (B).
f) EN61000-4-6 (2009) Conducted RF, 3V, 80% AM at 1kHz (AC line only; DC Output
connections <3m, therefore not tested†), Performance A (A).
†signal lines were not tested on the basis that typical use will be with connections <3m, for which
there is no test requirement. Immunity performance with connections >3m is not guaranteed.
According to EN61326-1 the definitions of performance criteria are:
Performance criterion A: ‘During test normal performance within the specification limits.’
Performance criterion B: ‘During test, temporary degradation, or loss of function or performance
which is self-recovering’.
Performance criterion C: ‘During test, temporary degradation, or loss of function or performance
which requires operator intervention or system reset occurs.’
*Performance B is stated because DC Output regulation, or V & I measurement accuracy, may
deviate beyond Specification limits under the test conditions. However, the possible deviations are
still small and unlikely to be a problem in practice. Minor deviations are possible at 300-350MHz,
670-740MHz and 810-820MHz at 3V/m.
Note that if operation in a high RF field is unavoidable it is good practice to connect the PSU to the
target system using screened leads which have been passed (together) through an absorbing
ferrite sleeve fitted close to the PSU terminals.
Cautions
To ensure continued compliance with the EMC directive observe the following precautions:
a) after opening the case for any reason ensure that all signal and ground connections are remade
correctly and that case screws are correctly refitted and tightened.
b) In the event of part replacement becoming necessary, only use components of an identical type,
see the Service Manual.

7
Safety
This power supply is a Safety Class I 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% 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 defective, 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.
l
mains supply ON.
alternating current (ac)
direct current (dc)
Caution – risk of danger. Refer to the documentation (this manual) to find
out the nature of the potential hazard and any actions which have to be taken.

8
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
Connect the instrument to the AC supply using the mains lead provided. Should a mains plug be
required for a different mains outlet socket, a suitably rated and approved mains lead set should
be used which is fitted with the required wall plug and an IEC60320 C13 connector for the
instrument end. To determine the minimum current rating of the lead-set for the intended AC
supply, refer to the power rating information on the equipment or in the Specification.
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.
Mounting
This instrument is suitable both for bench use and rack mounting. It is delivered with feet for bench
mounting. The front feet include a tilt mechanism for optimal panel angle.
A rack kit for mounting in a 19” rack is available from the Manufacturers or their overseas agents.
Ventilation
The power supply is cooled by intelligent multi-speed fans which vent at the rear. Take care not to
restrict the air inlets at the front (top, bottom & side panels) or the exit at the rear. In rack-mounted
situations allow adequate space around the instrument and/or use a fan tray for forced cooling.

9
Connections
Rear Panel Connections
Output Terminals (each output)
The load should be connected to the positive (red) and negative (black) terminals marked
OUTPUT. The terminals accept 4mm plugs into the end (but note that 4mm plugs will only support
30 Amps), 6mm diameter wire or plugs into the cross-hole or 8mm spade connections (with a
maximum blade width of 16mm). The wiring and connectors must be capable of supporting the
current required; for 50 Amps, 6mm2cable is needed.
Remote sense connections to the load, if required, are made from the positive (+) and
negative (−) REMOTE SENSE terminals. Remote sense operation is selected from the keyboard
or via a remote control interface; R/SNS (Remote Sense) shows in the display beside the output
status ( OFF, CV, CI or UNREG ) when remote sense is selected and goes off when remote
sense is deselected.
The M4 threaded opening marked
provides a connection point to safety earth ground.
Warning! Voltages above 70Vdc are hazardous live according to EN 61010-1 and great care must
be taken when using the power supply at voltages above this level.
Always ensure that connections to the terminals are only made in a manner that does not
compromise the protection provided by the terminals themselves.
Ensure that the contact parts of all connecting wires are fully inserted and inaccessible to the touch.
Always make connections to the instrument with the OUTPUT off.
Logic Input (each output)
LOGIC IN is connected directly to the input of an isolating opto-coupler; there is no series resistor.
The input is activated when a current greater than approximately 1mA is forced between LOGIC IN
and LOGIC COMMON. The function of LOGIC IN is set from the keyboard.
Do not force a current exceeding 25mA between the terminals. Do not apply a voltage to LOGIC IN / LOGIC COMMON exceeding 50V with respect to .
Logic Output (each output)
LOGIC OUT is the open-collector output of an opto-isolated NPN transistor that will sink up to 2mA
when active (‘switch closure’). The function of LOGIC OUT is set from the keyboard.
The maximum voltage that can be applied between LOGIC OUT and LOGIC COMmon is 30VDC.
Do not apply external voltages between the terminals exceeding 30VDC.
Analogue Control (each output)
V CONTROL and I CONTROL inputs provide quasi-analogue control of the Output Voltage and
Current Limit respectively. The inputs are read 4 times per second by the A-to-D converter and the
output is set according to the selected input scaling. The input scaling for both can be set as 0 to
10 Volts or 0 to 5 Volts for range maximum output. The Analogue Control functions and scaling are
both selected from the keyboard.
The V CONTROL and I CONTROL inputs are differential, with a limited common mode range of
± 2.5Vdc with respect to the negative output. They should be driven from a ‘floating’ source such
as another power supply.
Do not apply external voltages between the terminals exceeding 20Vdc.

10
Analogue Monitor (each output)
The output terminal voltage and output current may be monitored on V MONITOR and I MONITOR
respectively. The output scaling for both is the same as that set for V CONTROL and I CONTROL,
see previous section.
The Analogue Monitor outputs should be connected to a measuring system with ‘floating’ inputs
such as a DMM.
Do not apply external voltages to these terminals.
RS232 (QPX600DP only)
9−pin female D−connector with pin connections as shown below. Can be connected to a standard
PC port using a fully wired 1:1 male-female cable without any cross-over connections.
Pin
Name
Description
1 RI Passively asserted (+V through 10kΩ)
2 TXD Transmitted data from instrument
3
RXD
Received data to instrument
4 CTS
5 GND Signal ground
6 RTS Passively asserted (+V through 10kΩ)
7
DSR
No internal connection
8 DTR
9 CD No internal connection
Signal ground is connected to instrument ground.
USB (QPX600DP only)
The USB port is connected to instrument ground. It conforms with USB 2.0 (Full Speed) and
accepts a standard USB cable. The Windows plug-and-play functions should automatically
recognise that the instrument has been connected. If the correct driver is not found, follow the
Windows on-screen prompts and install the required files from the CD supplied.
LAN (QPX600DP only)
The LAN interface is designed to meet LXI ( Lan eXtensions for Instrumentation) version 1.2;
the instrument is Class C compliant. Remote control using the LAN interface is possible using a
TCP/IP Socket protocol. The instrument also contains a basic Web server which provides
information on the unit and allows it to be configured. 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 recessed switch on the rear panel (marked LAN
RESET) to reset the unit to the factory default.
Further details are given in the Remote Operation chapter. For more information on LXI standards
refer to www.lxistandard.org/home
GPIB (QPX600DP only)
The GPIB signal grounds are connected to the instrument ground. The implemented subsets are:
SH1 AH1 T6 L4 LEO SR1 RL2 PP1 DC1 DT0 C0 E2
The GPIB address is set from the front panel.

11
Initial Operation
This section of the manual is a general introduction to the controls and operation of the instrument
and is intended to be read before using the power supply for the first time. In this manual front
panel keys, connections and indicators are shown in capitals, e.g. ESCAPE, JOG SET, OUTPUT,
ON. Messages shown on the display are printed in a different type-font, e.g. Enter V,
Limits,CV,Store.
Switching On, Output On/Off
The power switch is located at the bottom left of the front panel.
At power-up the default behaviour is for the instrument's settings to be restored to those
automatically saved when it was switched off, but with the outputs in independent mode and
always off ( OFF is shown at the top right-hand side of each output’s display). However, the user
can change this default setting such that the power-down status of the individual outputs and of the
tracking mode are restored at power-up, see the Extra Functions section.
Each DC Output is switched on and off electronically with alternate presses of its key; the ON
lamp illuminates when the Output is on. At the same time the message above the VOLTS and
AMPS display changes from OFF to CV (constant voltage) or CI (constant current) to indicate
the present operating mode; should the load cause the instrument to operate outside its
guaranteed power range the display will instead show UNREG (unregulated). Alternatively, the
BOTH ON or BOTH OFF keys can be used to switch both outputs on or off together; the outputs
switch synchronously within <10µs of each other. Note that, if one output is already on and the
other off, BOTH ON will turn the off output on and BOTH OFF will turn the on output off.
Select Output
The output to be adjusted is selected by pressing CONTROL 1 or CONTROL 2; the corresponding
LED lamp will light to show which output is currently under the control of the numeric keypad or
rotary control. Note that the individual ON keys, as well as the BOTH ON and BOTH
OFF keys, will always operate regardless of which output is currently selected by the CONTROL
keys. Control of Output 1 is the default setting at power-up.
Keypad
Only the principles of operation are outlined here; the setting of individual parameters is given in
detail in later sections. The paramount consideration in designing the user interface has been to
make changing settings as 'safe' as possible (i.e. with minimal risk of accidentally applying
excessive voltages to a load) whilst achieving ease of use. This has been achieved by requiring
the user to confirm (OK) new numeric settings, with the option to ESCAPE at any point or even to
simply pause until the operation times-out and the instrument returns to its original settings. In
addition, display messages and LED indicators prompt, guide or warn the user such that entry or
control errors are minimised. Where some of these features (e.g. beeps) are considered
unnecessary by regular users, the option exists to disable them, see the Extra Functions section.
Press CONTROL 1 or 2 to select the output to be adjusted. Under normal conditions the numeric
keypad is disabled; any numeric key presses will simply be ignored. To set a voltage with the
keypad first press the V NUMERIC SET key; the VOLTS display changes to show the present set
value in a smaller font, with the message Enter V or ESC below it, and the OK lamp starts
flashing. The new value is then entered from the keyboard; as it is entered it is displayed directly
below the present setting, replacing the prompt message. At any time during entry the new setting
can be confirmed with the OK key, e.g. it is sufficient to key in 1, OK to change the setting to
1Volt. When OK is pressed the display reverts to show just the new setting in the full-size font and
the OK lamp stops flashing; if OK is not pressed within 10s of the last numeric key the entry is
cancelled and the display returns to its original setting. If ESCAPE is pressed anytime in the entry
procedure, entry is cancelled and the display returns to its original setting. The current limit is set in
exactly the same way after first pressing I NUMERIC SET.
The OK key is used to confirm most keypad entries. At all other times it becomes the VIEW V/I
LIMITS key and pressing it will cause the display to show preset output voltage and current limit for
3 seconds; during this period the Limits message shows in the display.

12
Pressing SHIFT illuminates the ▲lamp and gives the numeric keys the functions marked above
them, e.g. STR (Store), RCL (Recall), etc. When a shift function is selected SHIFT is cancelled
(the ▲lamp is no longer lit). The further key presses required to complete the selected function
are described in detail in the sections that follow; if no key is pressed within 10 seconds to
complete the function, the function will terminate as if ESCAPE has been pressed. SHIFT is a
toggle key; pressing SHIFT again when it has been selected will cancel SHIFT. SHIFT is also
cancelled by ESCAPE, or by pressing SET V or SET I.
Jog Control
The rotary 'jog' control permits the output voltage or current limit to be incremented or
decremented in steps with a resolution set by the JOG SET keys; the output immediately follows
the setting, i.e. no OK is required.
Press CONTROL 1 or 2 to select the output to be adjusted. At power-up jog is always off. To jog
the voltage or current setting press the V or I JOG SET key; the associated lamp will illuminate and
the appropriate parameter display now changes to two lines. With the output ON the top line
continues to show the actual output, but the additional lower display now shows the present
Limits value; in the lower display, the JOG indicator ( ) is positioned under the digit that was last
jogged. Whilst the V or I JOG SET indicator is lit, each further press of the V or I key moves the
JOG indicator one digit to the left; the selection 'wraps-round' such that when the largest value of
jog increment has been reached the next press returns it to the lowest. The default position at
power-up is under the LSD, i.e. the lowest jog increment is selected.
Turning the rotary jog control clockwise/anti-clockwise increments/decrements the selected digit;
digits to the left of the one being jogged are automatically incremented/decremented when the
decade overflow/underflow point is reached. Digits to the right of the one being jogged remain
unchanged unless the jog step overflows/underflows the maximum/minimum settings in which
case they are set to zero. For example, 59·861V goes to 59·961V goes to 60·000V for a 0.1V jog
increment; 1.60A goes to 0·60A goes to 0·01A for a 1A jog decrement.
The jog steps that can be selected are 1mV, 10mV, 100mV and 10mA, 100mA, 1A.
To disable the jog rotary control press the JOG SET OFF key; reselecting JOG SET V or I will
enable jog on the last used digit position. Jog is not cancelled by using numeric entry or any of the
SHIFT functions but it is disabled whilst that function is enabled. Jog is disabled when control is
switched to the other output using the CONTROL 1 or 2 keys but is automatically enabled again
when control is switched back.
Note that the dual display of the parameter being jogged is primarily of use if the output is ON; with
the output off both lines of the display show the Limits value and change simultaneously as the
parameter is jogged.
Display
At power-up the display briefly shows the instrument model number and installed firmware revision
in the left-hand display before both displays revert to the standard status display.
The standard status display shows the voltage range and output voltage on the left (above the
front panel VOLTS marking) and the current on the right (above the front panel AMPS marking)
together with the present output status, i.e. OFF, CV, CI, or UNREG; if the output is off then
Limits is also shown in the display above the V and I values. The status of the LAN connection
is also shown in the top left corner of the display, as required for LXI compliance. Refer to the
'LAN Status Indication' paragraph in the LAN Interface section for details. During other operations,
however, the display capabilities are used more extensively to show, for example, prompts during
function settings, e.g. memory store and recall operations or the extra functions accessed via the #
shift function; details are given in the relevant sections of this manual.
The display contrast is set at the factory but can be adjusted from the keyboard to optimise it for
particular ambient operating conditions. Press SHIFT, # , select Extra Function 90, and follow the
on-screen prompts. Contrast can be adjusted independently for the two displays.

13
Manual Operation – Independent Mode
New users should first read the Initial Operation chapter which describes the operating principles
of the keypad and rotary jog control.
The default mode at power-up is ‘Tracking Off’, i.e. the two outputs are fully independent. The
following sections describe operation of either output in this mode. See the later ‘Manual
Operation – Link Menu’ chapter for details of the various tracking modes that can be set.
Set Voltage Range
There are two voltage ranges for each output – a low range (0 to 60V) and a high range (0 to 80V).
To select the range press SHIFT followed by RANGE. Changing to the higher range is always
possible and the display will show Select 0 to 80V range: 2mV resolution. OK to
confirm, ESC to cancel; pressing OK accepts the change. Because the resolution of the
80V range is 2mV the set-point will rounded down, if necessary, to the nearest 2mV figure (e.g. if
output is set to 59.997 it will be changed to 59.996).
When changing to the low range the display will show Select 0 to 60V range: 1mV
resolution. OK to confirm, ESC to cancel unless the output is set above 60V in which
case the display will show Can’t select 0 to 60V range. Set point too high. Esc
to cancel. The output must first be set to <60V before the low range can be selected.
Set Voltage
With the output off, the standard status display shows the set voltage; Limits shows as a
reminder beside OFF in the top line of the display. With the output ON the mode changes to CV
(constant voltage) or CI (constant current), depending on the set current limit and load conditions,
and the display shows the actual output voltage (measured at the sense point); note that in CI
mode the actual output voltage will be less than the set voltage. Both the set and actual voltage
are shown to a resolution of 1mV (0-60V range) or 2mV (0-80V range). If the set voltage and load
conditions cause the instrument to operate outside its guaranteed power range the display will
show UNREG (unregulated) and the actual output voltage will again be less than the set voltage.
The voltage can be set directly from the numeric keypad: press the NUMERIC SET V key, enter
the new value using the numeric keys and confirm by pressing OK. The broad principles of
keypad entry are explained in the Initial Operation chapter, which should be read by new users.
When SET V is pressed the VOLTS display changes to show the present set value in a smaller
font, with the message Enter V or ESC below it, and the OK lamp starts flashing. The new
voltage is then entered from the keyboard, e.g. 12·345V is entered as 1, 2, ·, 3, 4, 5. As it is
entered it is displayed directly below the present setting, replacing the prompt message.
The minimum voltage setting is 0·000V; the maximum setting is 60·000V (0-60V range) or 80.000V
(0-80V range).
Pressing OK at any point will set the voltage entered with any remaining digits set to zero,
e.g. 1, 2, ·, 3, OK will set 12·300V; 1, OK will set 1·000V. When OK is pressed the set voltage is
changed and the display reverts to the standard status mode.
Pressing ESCAPE at any time during the sequence, or making no further key press within
10 seconds of the previous one will cause the display to return to its original reading before
SET V was pressed.
Entering a voltage outside the range maximum (including trying to enter 3 digits before the decimal
point) or trying to enter more than 5 digits will cause the buzzer to beep; the last key entry will be
ignored.
The voltage can also be set using the Jog control. Pressing JOG SET V will illuminate the V JOG
SET lamp and the VOLTS display will again change to two lines. With the output ON the top line
continues to show the actual output, but the additional lower display now shows the present
Limits value; in the lower display, the JOG indicator ( ) is positioned under the digit that was last
jogged. Whilst the V SET lamp is lit, each further press will move the JOG indicator one digit to
the left; the selection 'wraps round' such that when the largest value of jog increment has been
reached the next press returns it to the lowest.

14
The default position at power-up is under the LSD, i.e. the lowest jog increment is selected. The
jog steps that can be selected are 1mV (2mV for the 0-80V range), 10mV and 100mV.
With jog enabled the output voltage can be incremented or decremented with the rotary jog control
with a step resolution indicated by the position of the JOG indicator. The output immediately
follows the setting, i.e. no OK is required. In CV (constant voltage) mode the actual output voltage
shown in the upper display line will follow the set voltage being ‘Jogged’ in the lower display;
however, if the output goes into constant current mode (indicated by the CV status message being
replaced by CI) the upper display, showing actual voltage, will show a value which is less than the
set voltage.
Note that the dual display during JOG SET V is primarily of use if the output is ON; with the output
off both lines of the display show the Limits value and change simultaneously as the voltage is
jogged.
Set Current Limit
With the output off, the standard status display shows the set current limit; with the output on it
shows the actual output current in all modes (CV, CI or UNREG). Both the actual current and the
current limit are shown to a resolution of 10mA.
The current limit can be set directly from the numeric keypad: press the NUMERIC SET I key,
enter the new value using the numeric keys and confirm by pressing OK. The broad principles of
keypad entry are explained in the Initial Operation chapter, which should be read by new users.
When SET I is pressed the AMPS display changes to show the present current limit value in a
smaller font, with the message Enter I or ESC below it, and the OK lamp starts flashing.
The new current limit is then entered from the keyboard, e.g. 12·34A is entered as 1, 2, ·, 3, 4. As
it is entered it is displayed directly below the present setting, replacing the prompt message.
The minimum current setting is 0·01A; the maximum setting is 50.00A, i.e. there is no over-range
capability.
Pressing OK at any point will set the current entered with any remaining digits set to zero,
e.g. 1, 2 ·, 3, OK will set 12·30A; 1, OK will set 1·00A. When OK is pressed the current limit is
changed and the display reverts to the standard status mode.
Pressing ESCAPE at any time during the sequence, or making no key press within 10 seconds of
the previous one will cause the display to return to its original reading before SET I was pressed.
Entering a value outside the range maximum (including trying to enter 3 digits before the decimal
point) or trying to enter more than 4 digits will cause the buzzer to beep; the last key entry will be
ignored.
The current limit can also be set using the rotary jog control. Pressing JOG SET I will illuminate
the I JOG SET lamp and the AMPS display will again change to two lines. With the output ON the
top line continues to show the actual output, but the additional lower display now shows the
present current limit; in the lower display, the JOG indicator ( ) is positioned under the digit that
was last jogged. Whilst the I SET lamp is lit, each further press will move the JOG indicator one
digit to the left; the selection 'wraps round' such that when the largest value of jog increment has
been reached the next press returns it to the lowest. The default position at power-up is under the
LSD, i.e. the lowest jog increment is selected. The jog steps that can be selected are 10mA ,
100mA and 1A.
With jog enabled the current limit can be incremented or decremented with the rotary jog control
with a step resolution indicated by the position of the JOG indicator. The output immediately
follows the setting, i.e. no OK is required. With the output ON and in CV mode the upper line of
the display showing actual current will be a lower value than the current limit being ‘Jogged’ in the
lower display; however, if the output goes into constant current mode (indicated by the CV status
message being replaced by CI) the upper display, showing actual current, will follow the current
limit value being ‘Jogged’ in the lower display.
Note that the dual display during JOG SET I is primarily of use if the output is ON; with the output
off both lines of the display show the Limits value and change simultaneously as the current
limit is jogged.

15
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.
Power Limit
The maximum current at different voltage settings is limited by the power envelope illustrated
below:
The power envelope is set to give 80V/7.5A and 10V/50A under all supply conditions (both outputs
loaded); at lower output voltages the output power is restricted by the 50A current maximum.
When the power limit is exceeded, the status indication will change from CV or CC to UNREG. For
example, if the supply is set to 20V, with the current limit at maximum, and is connected to a 1Ω
load, 20 Amps will flow and the supply will be in CV mode. As the voltage across the load is
increased, the power into the load increases until, at about 24V, the power limit is exceeded and
the supply changes from CV to UNREG.
Output Power (V x A)
If SHIFT, V x A is pressed the display shows the product of measured output voltage x measured
current in the form nn.n VA. . The V x A value is updated at the same measurement rate as for
V and I. Pressing ESCAPE cancels V x A mode.
Calculated Load Impedance (V/A)
If SHIFT, V/A is pressed the display shows the calculated result of measured output voltage ÷
measured current; this is a sampled result which can be updated by further presses of the OK key.
Pressing ESCAPE cancels V/A mode.
The display shows the calculated nominal V/A value with a resolution of 5 significant digits (10µΩ
resolution for V/A <1Ω). The accuracy is calculated from the uncertainty of the individual voltage
and current measurements and is indicated by showing the minimum and maximum possible
values (in brackets) beside the nominal. The uncertainty is worst when either (or both) V and I are
small.
This function is extremely useful for measuring low impedances at high currents, e.g. RDS(on) of
power MOSFETs. Always use the Remote Sensing function to eliminate the effects of connecting
lead and contact resistance when making low value V/A measurements.
Current Measurement Averaging
Press SHIFT, IAVG to select current averaging; IAVG shows in the top line of the display beside the
mode status. The AMPS reading is still updated at the same rate (4 times per second) but the
value displayed is the rolling average of the last 4 current measurements made.
QPX600D & DP
Power Envelope

16
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.
Warning! Voltages above 70Vdc are hazardous live according to EN 61010-1 and great care must
be taken when using the power supply at voltages above this level.
Always make connections to the instrument with the OUTPUT off.
Remote Sensing
The instrument has a very low output impedance, but this is inevitably increased by the resistance
of the connecting leads and the contact resistance between terminals and leads. At high currents
this can result in significant differences between the indicated source voltage and the actual load
voltage (even two 2mΩconnecting leads will drop 0·2V at 50 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 capability.
This requires the sense terminals to be connected to the output at the load instead of at the
source; insert wires into the REMOTE SENSE terminals and connect directly to the load.
Warning! Voltages above 70Vdc are hazardous live according to EN 61010-1 and great care must
be taken when using the power supply at voltages above this level.
Ensure that the exposed end of the wire is fully inserted and inaccessible to the touch.
Always make connections to the instrument with the OUTPUT off.
Select remote sense by pressing SHIFT, SENSE; the message Turn On Remote sense?
OK to confirm, ESCAPE to cancel is shown in the display and the OK lamp flashes.
Press OK to confirm or press ESCAPE to exit without changing state. R/SNS (Remote Sense)
shows in the display beside the output status ( OFF, CV, CI or UNREG ) when remote sense is
selected. Remote sense is turned off by pressing SHIFT, SENSE again; the message Turn Off
Remote Sense? OK to confirm, ESCAPE to cancel is shown in the display and
the OK lamp flashes. Press OK to confirm or press ESCAPE to exit without changing state; the
R/SNS indication in the display goes off when remote sense is deselected.
To avoid instability and transient response problems, care must be taken to ensure good coupling
between each output and sense lead; this can best be done by twisting the leads together. An
electrolytic capacitor directly across the load connection point may also be beneficial.
The voltage drop in each output lead must not exceed 1 Volt.
Sense Miswiring Trip
The output will be tripped off if the voltage between an output terminal and its corresponding sense
terminal exceeds approximately 2V; this will happen if the sense wires are wired at the load to the
wrong output or if an attempt is made to draw power from the sense wires.
If the sense terminals are miswired in this way the output is turned off and the message Sense
Error – Check Connections is displayed. Pressing ESCAPE at this point removes the
message and the display now shows the preset voltage and current limit. When the cause of the
trip has been corrected the output can be turned on again.
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 300VDC.
The maximum permissible voltage between any terminal and earth ground ( ) is 300VDC
Warning! Voltages above 70Vdc are hazardous live according to EN 61010-1 and great care must
be taken when using the power supply at voltages above this level.
Always make connections to the instrument with the OUTPUT off.

17
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.
Note that the output terminals are rated at 60A maximum; if several outputs are operated in
parallel to source higher currents than this the junction should be made at a separate point, not
one of the terminals.
Over-Voltage Protection
Over-Voltage Protection (OVP) can be set from 2.0V to 90.0V. If the output voltage exceeds the
set OVP the output is immediately turned off (typically within 100µs), thus avoiding damage to the
circuit under test. The OVP circuit will trip if an excessive voltage is accidentally set from the front
panel or via a remote control interface, or is the result of a failure in the control circuitry of the
instrument itself. OVP will also trip if an excessive voltage is impressed across the terminals from
an external source; however, when the output is tripped off, the external voltage will still be present
and it is up to the user to remove the source to avoid possible damage.
To set OVP press SHIFT, OVP. The display changes to show only the present OVP setting together
with the prompt Numeric Entry: Range 2-90 ; the OK lamp flashes. Enter the new OVP
value using the numeric keypad, exactly as described for setting output voltage, and press OK to
confirm the new setting; to exit without entering a new value press ESCAPE. The factory default
setting is 90·0V.
If the OVP is tripped the display shows the message OVP - Press ESC to Reset and
the output is turned off. Pressing ESCAPE at this point removes the message and the display now
shows the preset voltage and current limit. When the cause of the OVP has been removed (or the
OVP limit changed) the output can be turned on again.
Note also that it is possible and valid to set OVP below the set voltage. If the supply is in constant
current mode the output voltage will be below the set voltage; OVP could be set such that is was
above the actual output voltage but below the set voltage. This could be used to trip the output
under a fault condition which caused the load impedance to increase and the actual output voltage
to therefore rise above the OVP point.
Over-Current Protection
Over-Current Protection (OCP) can be set from 2.0A to 55.0A. If the output current exceeds the
set OCP the output is shut down (typically within 100ms).
To set OCP press SHIFT, OCP. The display changes to show only the present OCP setting
together with the prompt Numeric Entry: Range 2-55 ; the OK lamp flashes. Enter the
new OCP value using the numeric keypad, exactly as described for setting the current limit, and
press OK to confirm the new setting; to exit without entering a new value press ESCAPE. The
factory default setting is 55·0A.
If the OCP is tripped the display shows the message OCP - Press ESC to Reset and the
output is turned off. Pressing ESCAPE at this point removes the message and the display now
shows the preset voltage and current limit. When the cause of the OCP has been removed (or the
OCP limit changed) the output can be turned on again.
Note also that it is possible and valid to set OCP below the set current limit. For example, the
power supply may be used to repetitively test a unit under test (UUT) which normally takes a peak
current of, say, 10 Amps. However, a faulty UUT would take a current of more than 10 Amps and
would be damaged by being left in a 10 Amp current-limited state. In this case the current limit
could be set to 11A, say, and the OCP set to 10A to ensure that a faulty UUT will trip the supply off.

18
Output Protection
In addition to OVP and OCP for forward over-voltage and over-current protection, the output is
protected from reverse voltages by a diode; the continuous reverse current must not exceed
3 Amps although transients can be much higher.
Temperature Trip and Other Faults
If the safe internal temperature limit is exceeded because, for example, the fan vents have been
blocked, the output is automatically tripped off. The display will show a message indicating that a
fault has occurred and that the AC supply must be turned off and on again to reset the unit. If
over-temperature is suspected, the cause of the fault should be rectified and the unit allowed to
cool before the AC supply is turned on again.
Note that an over-temperature trip shuts down the primary side of the instrument and it is that
condition that is detected and causes the fault message to be displayed. However, other faults
may occur which would also cause the primary side to shut down and these will not be
distinguishable from an over-temperature trip. If the unit does not restart after being allowed to cool
then another fault might be present and the unit should be returned for service.
Logic Control Input and Output
Digital signal connections LOGIC IN and LOGIC OUT are available on the rear panel; press the
orange actuators of the screwless terminals, insert the connecting wire and release the actuator to
secure the connection. LOGIC IN is connected directly to the input of an isolating opto-coupler;
there is no series resistor. The input is active when an input current greater than approximately
1mA is forced between LOGIC IN and LOGIC COMMON. LOGIC IN can be set to enable the
output, disable the output, or be ignored when it is activated, see the Extra Functions section. Note
that LOGIC IN can only be used to enable/disable the output if the output has already been turned
ON with the front panel key or by remote interface command; this permits the front panel
key to be used to turn the output off in an emergency, i.e. to override LOGIC IN. Note also that,
having turned the output ON with the key, the ON lamp remains lit even when the output is
disabled by the LOGIC IN signal.
LOGIC OUT is an isolated rear-panel open-collector output that will sink up to 2mA when active
(‘switch closure’); the maximum voltage that can be applied to LOGIC OUT is 30Vdc. LOGIC OUT
can be set to be ‘closed’ or ‘open’ for output enabled or disabled, current limit (CI mode), power
limit (UNREG mode), or for any fault trip. The default condition is for LOGIC OUT to be ‘closed’ for
the Output ON; loss of AC power, which would deactivate the opto, is also reliably detected with
this setting. See Extra Functions section for further details.
Analogue Control
Rear panel connections V CONTROL and I CONTROL provide quasi-analogue control of the
Output Voltage and Current Limit respectively. The inputs are read 4 times per second by the
A-to-D converter and the output is set according to the selected input scaling. The input scaling for
both can be set as 0 to 10 Volts or 0 to 5 Volts for range maximum output. The Analogue Control
functions and scaling are both selected from the keyboard, see Extra Functions section.
The V CONTROL and I CONTROL inputs are differential, with a limited common mode range of
± 2.5Vdc with respect to the negative output. They should be driven from a ‘floating’ source such
as another power supply.
Analogue Control is activated from the Bus menu, see Remote Operation section. When
activated, the top line of the display shows which functions (V and/or I) have been selected and the
corresponding functions on the front panel (NUMERIC SET / JOG SET for V and/or I ) are inhibited
to avoid contention between Analogue Control and front panel operation.
Analogue Monitor
The output terminal voltage and output current may be monitored on V MONITOR and I MONITOR
respectively. The output scaling for both will be the same as that set for V CONTROL and I
CONTROL, see above section. V MONITOR and I MONITOR are always available at the rear
panel terminals and should be connected to a measuring system with ‘floating’ inputs such as a
DMM.

19
Store Settings
The instrument can store 10 set-ups in non-volatile memory; the parameters stored are voltage,
current limit, OVP and OCP. The output state and remote sense setting are not stored.
To store a set-up press SHIFT, STORE to show the store locations and the currently saved set-ups
on the Store screen.
The store location to be used can be selected directly by pressing any key 0 – 9 or by scrolling to
the appropriate store number in the list using the JOG SET control; the selected store is indicated
by the square brackets [ ] at that location. Press OK to store the set-up at the selected
location; the screen returns to the standard status display. A full store can be overwritten with new
settings. At any time before the OK key is pressed the store function can be exited without saving
a set-up by pressing ESCAPE or by waiting for the operation to time out.
Deleting Stored Settings
Any store can be returned to 'empty' as follows: press SHIFT, STORE, and select the appropriate
store number as described in the Store Settings section above; at that point press ·followed by
OK to confirm the operation. At any time before the OK key is pressed the delete function can be
exited without erasing a set-up by pressing ESCAPE or by waiting for the operation to time out.
Recall Settings
To recall a set-up press SHIFT, RECALL to show the store locations and the currently saved set-
ups on the Recall screen. Each store location is displayed with its output voltage, current limit,
OVP and OCP settings; the output status (on/off) and sense settings (local/remote) are not stored.
Empty store locations are shown without data.
The store location containing the setting to be recalled can be selected directly by pressing any
key 0 – 9 or by scrolling to the appropriate store number in the list using the JOG SET control; the
selected store is indicated by the square brackets [ ] at that location. Press OK to recall the
set-up at the selected location; the screen returns to the standard status display. Settings may be
recalled with the output on or off.
Extra Functions
Options for extra functions such as LOGIC CONTROL and ANALOGUE CONTROL/MONITOR,
plus variations on some of the factory default functions, can be set by the user by using the # extra
functions facility. The complete list of functions is accessed by pressing SHIFT, # ; the required
function can be selected directly by entering nn from the keyboard, where nn is the 2-digit number
in the list below, or by scrolling to the appropriate function in the list using the JOG SET control;
the selected function is indicated by the square brackets [ ] at that position in the list. Press
OK to initiate the selected function, following the on-screen prompts where appropriate. At any
time before the OK key is pressed the extra function can be exited without implementation by
pressing ESCAPE or by waiting for the operation to time out.
Selected functions are indicated by a

beside the code in the on-screen list. Note that the
options within any decade group are mutually exclusive and selecting a function within any group
will automatically deselect any previously selected function in that group, including the factory
default option; for example, if #26 is selected, 20 -25 and 27 are all deselected.
With the exception of functions 30/31 and 70/71 all extra functions are specific to a particular
output and will only be changed for the output currently selected by the CONTROL keys; the extra
functions can therefore be set differently for each output. Functions 30/31 (buzzer) and 70/71
(Tracking) apply to the whole instrument therefore changing the selection for output 1 will
automatically change the selection on output 2.