AimTTi QL Series II User manual

QL Series II
Precision Power Supplies INSTRUCTION MANUAL

1
Table of Contents
Introduction 2
Specification 4
Safety 7
Installation 8
Connections 9
Front Panel Connections 9
Rear Panel Connections 9
Initial Operation 11
Manual Operation 14
Main Outputs 14
Main Outputs – Link Mode (T models only) 21
Main Outputs – Copy Function (T models only) 23
Auxiliary Output (T models only) 23
Remote Operation (P models only) 24
Interface Locking 24
Address & Baud Rate Selection and Interface Status View 24
Remote/Local Operation 25
RS232 Interface 25
USB Interface 26
LAN Interface 26
Status Reporting 30
Remote Commands 34
RS232/USB Remote Command Format 34
GPIB Remote Command Formats 34
Command List 35
Maintenance 40
Note: The latest revisions of this manual, device drivers and software tools can be
downloaded from: http://www.aimtti.com/support.
This manual is 48511-1560 Issue 8

2
Introduction
Unmatched Precision, Unrivalled Performance
The QL series II provides the highest performance levels available in a laboratory power supply.
Voltage and current are controlled using 16 bit DACs enabling voltages to be set to 1mV resolution
even at full output. Indeed, the accuracy is sufficient for the PSU to be used as a calibration
source for some hand-held DMMs.
The QL series II uses pure linear technology and offers unrivalled performance in terms of
regulation, output noise and dynamics. Line and load regulation are close to the limit of
measurement. Output noise is less than 350µV rms in CV mode and down to 20µA rms in CI
mode. Recovery time from transient current pulses is better than 50µs.
It provides full remote sense capability via dedicated sense terminals. Remote sense is essential
to maintain precise regulation at the load. When remote sense is not required, internal local
sensing can be selected at the touch of a button.
Multiple Ranges for Greater Flexibility
The QL series II provides multiple ranges for increased current capability at lower voltages. The
main range offers 0 to 35 Volts at up to 3 Amps (QL355) or 0 to 56 Volts at up to 2 Amps (QL564).
The higher current range provides up to 5 Amps for voltages up to 15V (QL355) or 4 Amps for
voltages up to 25V (QL564). A further low current range provides enhanced current setting and
measurement resolution of 0·1mA.
The product of voltage and current can be displayed at any time by pressing the VxA button. The
power is displayed to a resolution of 0·01 Watts.
Fast, Simple and Safe to use
The user interface of the QL series II has been carefully designed to provide rapid control whilst
guarding against any possibility of error.
Voltage and current setting can be performed either by direct numeric entry or, for applications
where the voltage or current must be gradually changed, by using the quasi-analogue Jog control.
To enable the current limit to be set before connecting the load, the limit setting is displayed when
the output is off. Pressing the View Limits key at any time provides a temporary display of the limit
values allowing precise adjustment to also be made with the output on.
Setting Memories for Added Convenience
The QL series II provides storage of up to 50 power supply sets-ups in non-volatile memory for
each main output, plus (T models only) a further 50 set-ups for linked mode operation, plus 10 set-
ups for the auxiliary output. Upon mains switch-off, the set-up of the PSU is saved and is
automatically restored at switch-on.
OVP and OCP Trips with 'Alarm' Output
The QL series II provides fully adjustable over-voltage and over-current trips which can be used
both as a fail-safe against accidental mis-setting and as a protection against inappropriate load
conditions. In addition to turning the output off, a trip condition switches the rear panel alarm
signal enabling other equipment to be controlled.
For complete protection of the power supply, the trip will also be operated by over-temperature or
excess voltage on the sense terminals.
Auxiliary Output with Fully Variable Voltage (T models)
The QL series II triple output power supplies incorporate an auxiliary output which is fully variable
between 1 volt and 6 volts to a resolution of 0.01V, and has a current capability of 3 amps.
A front panel button enables to voltage and current for the auxiliary output to be viewed on the
Output 1 display whenever required.

3
Fully Programmable via GPIB, RS232, USB or LAN
The programmable ‘P’ models incorporate a full bus interface permitting remote control and
readback via either GPIB (IEEE-488), RS232, USB or LAN.
The GPIB interface conforms fully with IEEE-488.2 and IEEE-488.1.
The RS232 interface uses a standard 9-pin D-connector and has a Baud rate variable from 600
to 19200.
The USB interface is compatible with USB 2.0 and USB 1.x.
The LAN interface is 1.4 LXI Core 2011 compliant.
The QL series II uses simple and consistent command structures which make programming
particularly easy regardless of which interface is used.
An IVI driver for Windows is included. This provides support for common high-level applications
such as LabView*, LabWindows*, and HP/Agilent VEE*.
All power supply settings can be controlled via the bus. Voltage and current can be set to a
resolution of 1mV or 0·1mA (main outputs). Actual voltage and current can be read back
together with the power supply status.
* LabView LabWindows is a trademark of National Instruments Corp. Agilent VEE is a trademark of Agilent Technologies inc.

4
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.
MAIN OUTPUTS
Voltage/Current Ranges:
QL355
QL564
0V to 35V/0·001A to 3A
0V to 35V/0·1mA to 500mA
0V to 15V/0·001A to 5A
0V to 56V/0·001A to 2A
0V to 56V/0·1mA to 500mA
0V to 25V/0·001A to 4A
Voltage Setting: Resolution 1mV
Accuracy ± (0·03% + 5mV)
Current Setting: Resolution 1mA; 0·1mA on 500mA range
Accuracy ± (0·2% + 5mA); ± (0·2% + 0·5mA) on 500mA range.
Output Mode: Constant voltage or constant current with automatic cross-over.
CI indicator lit in constant current mode.
Output Switch: Electronic, non isolating. Switch illuminated when Output on.
Preset voltage and current limit displayed when Output off.
Output Terminals: Universal 4mm safety binding posts on 19mm (0·75”) pitch for Output;
screwless terminals for Sense.
Duplicate rear panel Output and Sense screw terminals on P models.
Transient Response: <50µs to within 15mV of set level for a change in load current from full
load to half load or vice versa.
Voltage Programming
Speed:
Maximum time required for output to settle within 1% of its total
excursion (for resistive load). Excludes command processing time.
QL355
QL564
Full Load No
Load
Full Load No
Load
Up
Up
Up
15V 5A
35V 3A
35V 500mA
6ms
20ms
200ms
6ms
7ms
40ms
25V/4A
56V/2A
56V/500mA
10ms
40ms
300ms
6ms
15ms
60ms
Down
Down
Down
15V 5A
35V 3A
35V 500mA
6ms
25ms
120ms
250ms
600ms
600ms
25V/4A
56V/2A
56V/500mA
10ms
50ms
200ms
400ms
800ms
800ms
Ripple and Noise
(20MHz bandwidth):
Normal mode voltage: <0·35mVrms and 2mVp-p
Normal mode current: <0·2mArms; <20µArms on 500mA range.
Load Regulation: For any load change, measured at the output terminals, using
remote sense.
Voltage <0·01% + 2mV.
Current <0·01% + 250µA; <0.01% +50µA on 500mA range.
Add typically 2·5mV for a 0·5V drop in the positive output lead.
Specification applies for sense lead resistance <0·5Ω.
Line Regulation: Voltage <0·01% + 2mV for 10% line change.
Current <0·01% + 250µA; <0.01%+ 50µA on 500mA range.
Temperature Coefficient: Voltage: typically <(50ppm + 0·5mV)/°C
Current: typically <(100ppm + 1mA)/°C;
typically<(100ppm + 0·1mA)/°C on 500mA range.

5
Output Protection: Output will withstand forward voltages of up to 20V above rated output
voltage. Reverse protection by diode clamp for currents up to 3A.
Over-voltage Protection:
(OVP) Range 1V to 40V (QL355), 1V to 60V (QL564) Resolution 0·1V; accuracy ± (2% + 0·5V)
Response time typically 100µs
Over-current Protection:
(OCP) Range 0·01A to 5·5A (QL355), 0·01A to 4·4A (QL564) Resolution 0·01A; accuracy ± (0·2% + 0·01A)
Response time typically 35ms
Protection Functions:
Output trips off for OVP, OCP, over-temperature and Sense miswiring
METER SPECIFICATIONS (Main Outputs)
Display Type:
5-digit (Volts), 4-digit (Amps), 14mm (0·56") LED.
Voltage (CI mode): Resolution 10mV
Accuracy ± (0·1% of reading + 10mV)
Current (CV mode): Resolution 0·001A; 0·1mA on 500mA range
Accuracy ± (0·2% + 0·005A); ± (0·2% + 0·5mA) on 500mA range
V x A: Resolution 0·01W; 0·001W on 500mA range
Accuracy ± (0·3% + 0·05W); ± (0·3% + 0·005W) on 500mA range
AUXILIARY OUTPUT (T models only)
Voltage Range:
1V to 6V
Voltage Setting: Resolution: 10mV
Accuracy: ± 0.5% ±10mV
Current Limit:
3A minimum
Output Switch:
Electronic, non isolating. Switch illuminated when Output on.
Output Terminals: Universal 4mm safety binding posts on 19mm (0·75”) pitch. Duplicate
screwless terminals on rear panel.
Output Protection: Output will withstand up to 16V forward voltage. Diode clamp reverse
protection for currents up to 1A. Over-current trip.
Ripple & Noise:
(20MHz bandwidth)
<2mV rms, 10mVp-p
Load & Line Regulation:
<1·0% for a 90% load change; 0·1% for a 10% line change.
Status Indication: Current limit lamp. Current overload trip indication.
Meter Specifications:
(use SET/VIEW button)
Voltage Meter: Resolution 10mV, accuracy ± 0.5% ±10mV
Current Meter: Resolution 10mA, accuracy ± 0.5% ±10mA
Voltage Programming
Speed:
Maximum time required for output to settle within 1% of its total
excursion (for resistive load). Excludes command processing time.
1V to 6V: 10ms, no load and full load
6V to 1V: 10ms, no load and full load
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.

6
ALARM OUTPUT
Isolated rear-panel open-collector output signal. User can select output to be activated for either
OVP, OCP, Overtemperature or Sense miswiring, or for any of those four faults.
DIGITAL INTERFACES (P models only)
Full digital remote control facilities are available through the RS232, USB, LAN and GPIB interfaces.
General
RS232:
Standard 9-pin D-connector. Variable Baud rate (600 to 19200).
GPIB:
Conforming with IEEE488.1 and IEEE488.2
USB:
Standard USB 2.0 hardware connection. Operates as a virtual COM port.
LAN:
Ethernet 100/10base-T hardware connection. 1.4 LXI Core 2011.
Remote Command
Processing Time: Typically <25ms between receiving the command terminator for a step voltage change at the instrument and the output voltage beginning to
change.
Status Indication:
Remote mode and LAN status indicators
Main Outputs
Voltage Setting:
16-bit; Resolution 1mV, accuracy ± (0·03% +5mV)
Current Setting: 16-bit; Resolution 0.1mA, accuracy ± (0·2% + 5mA)
Resolution 0.01mA, Accuracy ± (0·2% + 0·5mA) on 500mA range.
Readback V & I
See meter specifications.
Auxiliary Output (T models only)
Voltage Setting:
Resolution 10mV, accuracy ± 0.5% ±10mV
Current Setting:
Resolution 10mA, accuracy ± 0.5% ±10mA
Readback V & I
See meter specifications
GENERAL
AC Input: 230V AC or 115V AC ± 10%, 50/60Hz
Installation Category II
Power Consumption:
Single output: 250VA max; Triple output: 500VA 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.
Cooling: Intelligent variable-speed fan. Over-temperature trip shuts down
output if internal temperatures exceed predetermined thresholds.
Store/Recall: Up to 50 set-ups each main output, 50 linked set-ups, and 10 auxiliary
output settings can be saved and recalled via the keyboard or remote
interfaces.
Safety: Complies with EN61010-1 & EN61326-1.
For details, request the EU Declaration of Conformity for this
instrument via http://www.aimtti.com/support (serial no. needed).
Size: Single output: 140 x 160 x 290mm (WxHxD), excl. feet & terminals.
Triple output: 280 x 160 x 290mm (WxHxD), excl. feet & terminals
Weight: Single: 5.5kg; Triple: 10·5kg

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)

8
Installation
Check that the instrument operating voltage marked on the rear panel is suitable for the local
supply. Should it be necessary to change the operating voltage, proceed as follows:
1) Disconnect the instrument from all voltage sources.
2) Remove the screws which retain the top cover and lift off the cover.
3) Change the connections on both transformers following the appropriate diagram below:
BROWN BLUE BROWN BLUEBROWN
115V230V
4) Refit the cover and the secure with the same screws.
5) To comply with safety standard requirements the operating voltage marked on the rear panel
must be changed to clearly show the new voltage setting.
6) Change all three fuses to ones of the correct rating, see below.
Fuse The AC inlet fuse is located in the fuse drawer in the lower part of the IEC inlet connector. To
change the fuse remove the line cord and open the fuse drawer with a suitable tool.
QL355, QL355P, QL564 & QL564P
The correct mains fuse type is 20 x 5mm 250V HBC time-lag with the following rating:
for 230V operation:
1.6A (T) 250V HBC
for 115V operation:
3.15A (T) 250V HBC
QL355T, QL355TP, QL564T & QL564TP
The correct mains fuse type is 20 x 5mm 250V HBC time-lag with the following rating:
for 230V operation:
4A (T) 250V HBC
for 115V operation:
8A (T) 250V HBC
In addition, the two transformers are individually fused inside the power supply. To access these
fuses remove the cover as described above; both fuses are clipped to the small PCB which is
fitted directly onto the pins of the IEC inlet connector itself.
The correct fuse type is 20 x 5mm 250V HBC time-lag with the following rating:
for 230V operation:
1.6A (T) 250V HBC
for 115V operation:
3.15A (T) 250V HBC
Make sure that only fuses with the required current rating and of the specified type are used for
replacement. The use of makeshift fuses and the short-circuiting of fuseholders are prohibited.

9
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 QL Series power supplies is available from the Manufacturers or their
overseas agents. The rack will accommodate 1, 2 or 3 single units or a triple and single unit; a
blanking piece is also available for unused positions in the rack.
Ventilation
The power supply is cooled by an intelligent multi-speed fan which vents at the rear. Take care
not to restrict the air inlets at the 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.
Connections
Front Panel Connections
The loads should be connected to the positive (red) and negative (black) terminals marked
OUTPUT 1, OUTPUT 2, or AUX.
Remote sense connections to the loads on Outputs 1 or 2, if required, are made from the
corresponding positive (+) and negative (−) REMOTE SENSE terminals. Remote sense
operation is selected from the keyboard or via a remote control interface (P models only); the
REMOTE SENSE lamp is lit when remote sense is selected. Switching off remote sense returns
the instrument to local sensing at the output terminals.
The terminal marked is connected to the chassis and safety earth ground.
Rear Panel Connections
Main Output Terminals (P models only)
The output and sense terminals are duplicated on the rear panel screw-terminal block marked
Output +, Output −, Sense + and Sense −; these connections are paralleled with their front panel
equivalents.
Remote sense operation is selected from the keyboard or via a remote control interface. When
the rear panel terminals are used, remote sense should always be selected to ensure that output
regulation is maintained within specification.
Auxiliary Output Terminals (T models only)
The front panel AUX OUTPUT terminals are duplicated on the rear panel with screwless
terminals marked AUXILIARY OUTPUT.

10
Alarm Outputs
Associated with each main output are recessed 2-pin connectors marked Alarm. These provide
access to an opto-isolated NPN switching transistor, the function of which can be set from the
keyboard, see the Alarm Output section of this manual.
The maximum operating voltage that can be applied across the terminals is 20VDC and the
maximum sink current for the switch 'closure' is 1mA.
Do not apply external voltages between the terminals exceeding 30VDC.
RS232 (P models 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 (P models 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 (P models only)
The LAN interface is designed to meet 1.4 LXI ( Lan eXtensions for Instrumentation) Core 2011.
. 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 (P models only)
The GPIB signal grounds are connected to the instrument ground. The implemented subsets are:
SH1 AH1 T6 TE0 L4 LE0 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 display indicators are shown in capitals,
e.g. STORE, ESCAPE, OUTPUT, JOG. Messages shown on the 7-segment display are printed
in a different type-font, e.g. StorE, GPIb, triP in upper or lower case to represent the
characters as they are shown on the 7-segment display.
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 all outputs always off. However, the user
can change the default setting such that selected outputs are restored at power-up to their status
at power-down, see the Extra Functions section.
The DC outputs are switched electronically with their respective ON/OFF keys; the key
illuminates when the output is on. In addition, all outputs can be switched on and off together
using the ALL ON and ALL OFF keys.
Synchronous Output On/Off Switching (T models only)
Pressing ALL OFF at any time will synchronously turn off any outputs that are on; under the same
load conditions outputs will typically turn off within 1ms of each other. With all outputs off the ALL
OFF key is illuminated green. Pressing the ALL ON key when all the outputs are off will turn all
the outputs on synchronously; outputs with identical settings and load conditions will typically turn
on within 1ms of each other. However, if one output is already on, pressing ALL ON will turn the
remaining outputs on but the turn-on delay between the outputs will be up to 80ms, even with the
same output setting and load conditions.
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 target
system) 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 a buzzer, illuminated keys, LED indicators and display messages prompt, guide or
warn the user such that entry or control errors are minimised. Where some of these features
(e.g. beeps or flashing indicators) are considered unnecessary by regular users, the option exists
to disable them, see the Extra Functions section.
On triple output (T) models the ability to change settings from the keypad or by using the Jog
controls is assigned to Output 1, Output 2 or both by using the 1, 2 or LINK CONTROLkeys
respectively. The key (1 or 2) associated with the selected output illuminates to show which
output is under control. In LINK mode (both keys lit) both outputs are controlled at the same
time, including some of the shifted operations (RANGE, STORE, RECALL and V x A). The
further descriptions that follow apply to either or both main outputs as appropriate to the setting
indicated by the illumination of the CONTROLkeys.
Under normal conditions the numeric keypad is disabled; pressing any key will cause the buzzer
to make a double beep, indicating an illegal operation. To set a voltage or current with the
keypad press the V or I NUMERIC SET key; the appropriate display shows 0·000V or 0·000A
with the digit to the left of the decimal point flashing. Digits are entered in response to the
flashing prompt, together with the decimal point at the appropriate time, and the entry is
confirmed with the OK key. If OK is not pressed within 10 seconds of the last numeric key the
entry is cancelled and the display returns to its original setting. If ESCAPE is pressed anywhere
in the entry procedure, entry is cancelled and the display returns to its original setting.

12
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 LIM indicator in the display flashes.
Pressing SHIFT illuminates the key and gives the numeric keys the functions marked above them
(e.g. STORE, RECALL, etc.). When a function is selected by pressing one of these keys SHIFT
is cancelled (the SHIFT key 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. Note that in LINK mode
settings accessed by STORE and RECALL are specific to the LINK mode and are in addition to
settings accessible when STORE and RECALL are used on individually selected outputs.
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.
At power-up jog is always off. To jog the voltage or current setting press the V or I JOG SET key;
the key will illuminate and the JOG indicator under the digit that was last jogged will flash. Whilst
the V or I JOG SET key 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 range maximum/minimum in which case
they are set to zero. On the QL355, for example, 33·65V goes to 34·65V goes to 35·00V for the
35V range and a 1V jog increment; 0·160A goes to 0·060A goes to 0·001A for a 0·1A jog
decrement.
The jog steps that can be selected for the main range are 1mV, 10mV, 100mV and 1mA, 10mA,
100mA; if the 500mA range has been selected the current increment steps are 0·1mA, 1mA,
10mA.
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.
When in constant voltage mode, with the output on, the right-hand display will show actual
current rather than current limit. If JOG SET I is selected the JOG indicator under the selected
digit will flash at half-speed ('lazy' flash). To observe the effect of jogging the current limit it will
be necessary to either turn the output off (so that the display permanently shows the current limit)
or to press VIEW V/I LIMITS which causes the current limit to be displayed until 3 seconds after
movement of the jog control ceases. The 'lazy' flash is also used when JOG SET V has been
selected and actual voltage is being shown because the supply has gone into current limit.
The factory default is to flash the JOG indicator under the selected digit for the whole time that
jog is selected so that the user is constantly reminded which parameter can be incremented/
decremented. Where this degree of reminding is considered inadequate the user can select,
using the Extra Functions capability, to flash the digit itself; conversely, where the flashing is
considered intrusive the user can select to not flash the JOG indicator (except when the 'lazy'
flash is shown).

13
Display
The displays shows the voltage on the left (5 digits) and the current on the right (4 digits) for both
the main outputs. These 7-segment displays are also used to show prompts during some of the
function settings (e.g. memory store/recall or remote control address setting) using the limited
'character set' that can be achieved with a 7-segment display; these are necessarily a mixture of
upper and lower case letters.
Above and below the 7-segment display are several secret-until-lit annunciators.
To the right, above the current display, are the indicators which show the selected operating
range: 35V/3A, 15V/5A or 35V/500mA (QL355T & TP) or 56V/2A, 25V/5A or 56V/500mA
(QL564T & TP); the indicators light beneath the range printed immediately above them and, in
the case of the 500mA range, the indicator is marked mA to emphasise that the current display is
now showing mA.
The other annunciators above the displays are:
CI, indicating that the instrument is in constant current mode;
LIM, which flashes when the VIEW V/I LIMITS key is pressed to show the set voltage/set current
limit in the display;
REM, which lights when the instrument is under control from a remote interface (P models only)
and LAN, which indicates the status of the LAN interface connection (P models only).
Below the three least significant digits of both the voltage and current displays are the JOG
indicators; the appropriate indicator flashes when the jog function is being used, see the Jog
Control section above.
The display of Output 1 can alternatively be used to show the voltage and current of the AUX
output (T models only). Full details are given in the Auxiliary Output section.

14
Manual Operation
Main Outputs
New users should first read the Initial Operation chapter which describes the operating principles
of the keypad and rotary jog control. The following paragraphs describe the independent
operation of either Main Output. To select which output is to be controlled by the keypad/Jog
controls it is first necessary to select that output by pressing the appropriate CONTROLkey
(1 or 2); the key lights to show that it is the selected output.
The additional features available on the triple output (T) models in LINK mode (both Main
Outputs selected) are described in the Main Outputs – Link Mode section later in this manual.
Set Voltage
The left-hand display shows the set voltage to a resolution of 1mV, except when the instrument is
in constant current (CI) mode. In CI mode the actual output voltage (which will be less than the
set voltage) is shown and the display resolution is 10mV; the least significant digit (1mV
resolution) is always displayed as a zero.
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 display shows 0·000; a new voltage is then entered (e.g. 12·345V is
entered as 1, 2, ·, 3, 4, 5) and confirmed by OK. The position of the decimal point in the display
is fixed to reduce the risk of entering a wrong value. As a consequence, and to avoid the need to
enter leading zeroes (e.g. 2·345V is entered as 2, ·, 3, 4, 5, OK), numbers to the left of the
decimal point are shown slightly differently to the numbers to the right of the decimal point during
number entry; this is self-evident during number entry.
The minimum voltage setting is 0·000V; the maximum setting for QL355 is 35·000V (15·000V on
the 15V/5A range) or 56.000V (25.000V on the 25V/4A range) for QL564.
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; pressing OK immediately after SET V
(while the display shows 0·000V) will set 0·000V.
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 twice; 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 key
and the JOG indicator under the digit that was last jogged will flash. Whilst the V key 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 1mV, 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 flashing JOG indicator. The output
immediately follows the setting, i.e. no OK is required. If the output goes into constant current
mode (indicated by the CI indicator flashing) the left-hand display shows actual voltage not set
voltage. If JOG SET V is selected the JOG indicator under the selected digit will flash at half
speed ('lazy' flash). To observe the effect of jogging the set voltage it will be necessary to either
turn the output off (so that the display permanently shows the set voltage) or to press
VIEW V/I LIMITS which causes the set voltage to be displayed until 3 seconds after movement of
the jog control ceases.

15
Note that in constant current mode the actual voltage is measured and displayed to only 10mV
resolution; the 1mV digit permanently displays zero.
Further details on the jog control can be found in the Initial Operation chapter.
Set Current Limit
With the output off, the right-hand display shows the current limit to a resolution of 1mA (0·1mA
on the 500mA range).
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 display shows 0·000; a new current is then entered (e.g. 1·234A is
entered as 1, · , 2, 3, 4,) and confirmed by OK. The position of the decimal point in the display is
fixed to reduce the risk of entering a wrong value. As a consequence, and to avoid the need to
enter or display leading zeroes (e.g. 0·234A is entered as ·, 2, 3, 4, OK), numbers to the left of
the decimal point are shown slightly differently to the numbers to the right of the decimal point
during number entry; this is self-evident during number entry.
The minimum current setting is 0·001A (0·1mA on the 500mA range); the maximum setting is
3·000A, 5·000A or 500·0mA (QL355) or 2·000A, 4·000A or 500·0mA (QL564), according to
range, 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, OK will set 1·200A; 1, OK will set 1·000A; pressing OK immediately after SET I (while
the display shows 0·000A) will set 0·00IA.
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 2 digits before the decimal
point) or trying to enter more than 4 digits will cause the buzzer to beep twice; 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 key and the JOG indicator under the digit that was last jogged will flash. Whilst the I key 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 1mA, 10mA and 100mA (0·1mA, 1mA and
10mA on the 500mA range).
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 flashing JOG indicator. The output
immediately follows the setting, i.e. no OK is required. With the output on, the right-hand display
shows actual current, not current limit (except in constant current mode). If JOG SET I is
selected the JOG indicator under the selected digit will flash at half speed ('lazy' flash). To
observe the effect of jogging the current limit it will be necessary to either turn the output off (so
that the display permanently shows the current limit) or to press VIEW V/I LIMITS which causes
the current limit to be displayed until 3 seconds after movement of the jog control ceases.
Instantaneous Current Output
The current limit control can be set to limit the continuous output current to levels down to 1mA
(0·1 mA on 500mA range). 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.

16
Range Selection
The instrument has three ranges: 35V/3A, 15V/5A and 35V/500mA (QL355) or 56V/2A, 25V/4A
and 56V/500mA (QL564). The selected range is shown by an illuminated indicator below the
appropriate legend at the top right-hand side of the instrument; when the 500mA range is
selected the indicator legend is mA to emphasise that the current meter now shows milliamps not
amps.
To change range press SHIFT followed by RANGE or RANGE; each press of RANGE
selects the next range to the left; each press of RANGEselects the next range to the right;
there is no 'wrap-round'. When the range is changed the indicator that represents the new range
and the OK key both flash; pressing OK sets the new range. To exit without changing range
press ESCAPE. Pressing any other key whilst in range change mode causes the warning buzzer
to beep twice; no other action is taken. If OK is not pressed within 10 seconds of the last range
change key press the range selection remains unchanged.
The range can only be changed when the output is off. Pressing the RANGE or RANGE 
keys with the output on will cause the output ON/OFF key (as well as the OK key) to flash. The
output may be turned off with the ON/OFF key and the range then changed by pressing OK, or
OK may be pressed directly in which case the output is automatically turned off and the range
then changed.
If a range change causes a voltage or current limit setting to exceed the corresponding maximum
of the new range the range change is accepted but the setting is made equal to the maximum of
the new range.
Note that the OVP setting is not changed when the range is changed (e.g., for QL355, an OVP
setting of 38V remains valid on the 15V range); it is left to the user to independently change the
OVP setting if required.
Output Settings – Front Panel Lock
To avoid accidental changes to the output settings in a bench or rack set-up, front panel control
of Range, Voltage, Current Limit, OVP and OCP can be ‘locked’ and ‘unlocked’ with alternate
uses of the #33 function, see Extra Functions section. The output ON/OFF key remains
unlocked, as does selection of remote sense. Front panel lock still operates in remote control
mode (P models only) but is ignored by the remote commands.
On triple output models the AUX output voltage is also locked when Output 1 settings are locked
but, additionally, the CONTROLkeys remain unlocked. All outputs are locked and unlocked
together if #33 is used in Link mode, see Auxiliary Output and Main Outputs-Link Mode sections.
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.
Remote Sensing
The instrument 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 20mΩconnecting 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
capability. 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 REMOTE SENSE terminals and connect directly
to the load.
Select remote sense by pressing SHIFT, SENSE; the OK key flashes and the lamp above the
remote sense terminals lights to show that remote sense will be selected when OK is pressed.
Press OK to confirm; press ESCAPE to exit without changing state. Remote sense is turned off
by pressing SHIFT, SENSE again; the OK key flashes and the remote sense lamp goes off to
indicate that local sense will be restored when OK is pressed. Press OK to confirm; press
ESCAPE to exit without changing state.

17
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.
The P models have rear panel output and sense terminals, appropriate for when the instrument is
used in a rack. The rear panel sense terminals should always be used with the rear panel output
connections.
Sense Miswiring Trip
The output will be tripped off if the voltage between an output terminal and its corresponding
sense terminal exceeds approximately 1V; 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 display shows the message SENSE triP
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 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 300V DC. 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 maximum permissible voltage between any terminal and earth ground ( ) is 300VDC.
WARNING! Such voltages are exceedingly hazardous and great care should be taken to shield
the 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.
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 30A 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 1·0V to 40V (QL355) or to 60V (QL564). If the
output voltage exceeds the set OVP the output is immediately shut down (typically within 100µs),
thus avoiding damage to the circuit under test. The OVP circuit will protect against accidental
excessive voltage settings from the front panel or via the remote control interfaces, external
voltages impressed across the output terminals, or a failure in the control circuitry of the
instrument itself.
To set OVP press SHIFT, OVP; the 100mV step JOG indicator will start flashing and the jog
rotary control can be used to increment/decrement the OVP setting in 100mV steps. Press OK to
confirm the new setting; to exit without entering a new value press ESCAPE. The factory default
settings are 40·0V (QL355) and 60V (QL564).
If the OVP is tripped the display shows the message OUP triP 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 that the OVP setting is not changed when the range is changed (e.g., for QL355, an OVP
setting of 38V remains valid on the 15V range); it is left to the user to independently change the
OVP setting if required. 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

18
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 0·01A to 5·5A (QL355) or to 4.4A (QL564). If the
output current exceeds the set OCP the output is shut down (typically within 35ms).
To set OCP press SHIFT, OCP; the 10mA step JOG indicator will start flashing and the jog rotary
control can be used to increment/decrement the OCP setting in 10mA steps. Press OK to
confirm the new setting; to exit without entering a new value press ESCAPE. The factory default
setting is 5·50A (QL355) or 4.4A (QL564).
If the OCP is tripped the display shows the message OCP triP 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 that as with OVP, the OCP setting is not changed when the range is changed.
Note also that 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, 2 Amps. However, a faulty UUT would take a current of more than 2 Amps
and would be damaged by being left in a 2 Amp current-limited state. In this case the current
limit could be set to 2·1A, say, and the OCP set to 2·0A to ensure that a faulty UUT will trip the
supply off.
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.
Output Power (V x A)
If SHIFT, V x A is pressed the voltage display shows the product of measured output voltage x
measured current and the current display shows UA ; the output power reading is continuously
updated at the normal measurement rate. Output Power mode is cancelled by pressing either
ESCAPE or V xA again. Jog is temporarily disabled (and the JOG indicators are turned off)
during the V x A display.
Temperature Trip
If the safe internal temperature limit is exceeded because, for example, the fan vents have been
blocked, the output is turned off and the display will show OtP triP. Pressing ESCAPE at
this point will do one of two things:
i. If the over-temperature condition has already cleared the message will be removed and the
display will show preset voltage and current limit. Assuming the cause of the over-temperature
has been rectified the output can be turned on again.
ii. If the instrument is still above the safe temperature limit the OtP triP message will flash
slowly ('lazy' flash) until the instrument has cooled, at which point the display will show preset
voltage and current limit again. Assuming the cause of the over-temperature has been
rectified the output can be turned on again.
Alarm Output
The recessed 2-pin connector on the rear panel is directly connected to an opto-coupled NPN
switching transistor (pin 1 emitter, pin 2 collector) which is turned on (i.e. switch 'closure')
according to the conditions specified in the Extra Functions section, see later. The default
condition is switch closure for any trip condition (OVP, OCP, SENSE or OTP). The maximum
open-circuit voltage permitted across the switch is 30VDC and the nominal sink current for switch
closure is 1mA.

19
Store Settings
The instrument can store 50 set-ups for each output in non-volatile memory; the parameters
stored are range, voltage, current limit, OVP and OCP. The output state and remote sense
setting are not stored. In addition, a further 50 Link Mode set-ups can be saved, see Main
Outputs – Link Mode section.
To store a set-up, first press SHIFT, STORE; the display shows Sto. on the left with the store
number (0 to 49) and store status (either Efor store Empty or F for store Full) on the
right. The SHIFT function is cancelled (the light goes off) at this point. The store number (0 to
49) can be set directly from the keypad or by using the Jog control to increment/decrement the
displayed number; the JOG indicator beneath the store number flashes to indicate that the Jog
control is active. Set the required store number by either method and press OK to store the
settings and return the display to showing V & I. The store function can still be used when the
output settings have been ‘locked’ using the #33 function. Afull 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 10 seconds from the last key entry.
Deleting Stored Settings
Any store can be returned to 'empty' as follows: press SHIFT, STORE, and set the required store
number via keypad or Jog control as described above; at that point press
•
. The display now
shows dEL in place of Sto , e.g. dEL 29 F ; pressing OK deletes the content of the
store. All of the output’s stored set-ups can also be deleted simultaneously by using the #98
function, see Extra Functions section.
Recall Settings
To recall a set-up, first press SHIFT, RECALL; the display now shows rEC. on the left with the
store number (0 to 49) and store status (either Efor store Empty or F for store Full) on
the right as each store is either selected in turn using the Jog control, or is set from the keypad
(as for storing set-ups, see above). The SHIFT function is cancelled (the light goes off) at this
point. If the store selected is full (F), the display changes to a flashing preview of the V & I
values of that store; press OK to recall the settings of the store and return the display to showing
V & I. If the store selected is empty (E), the display flashes ----- ---- to indicate this. It is
not possible to recall an ‘empty’ store (pressing OK gives a warning beep); either select a full
store or press ESCAPE to exit Recall. Recall cannot be used if the output has been ‘locked’.
At any time before the OK key is pressed the Recall function can be exited without recalling a
set-up by pressing ESCAPE or by waiting 10 seconds from the last key entry.
Settings may be recalled with the output on or off. However, if the recalled setting involves a
range change the output is turned off to avoid any 'glitches'. After pressing SHIFT, RECALL, and
setting the store number, the ON/OFF key will flash (as well as the OK key) if completing the
recall involves a range change. The output may be turned off with the ON/OFF key and the recall
then completed by pressing OK, or OK may be pressed directly in which case the output is
automatically turned off and the recall completed.
Extra Functions
Variations on some of the factory default functions can be set by the user by using the # extra
functions facility. Each function change, detailed in the list below is accessed by pressing SHIFT,
#, nn, when nn is the 2-digit number in the list below; the display changes to HASH No._after
SHIFT, # and the buzzer gives a confirmation beep when the 2-digit number entry is complete.
As indicated in the opening paragraph of this section, the # functions can be set independently
(i.e. differently) for each main output; note, however, that the #02, #03 and #21 functions which
apply to the Auxiliary Output can only be set when CONTROLis assigned to Output 1.
The settings of each Main Output can be ‘locked’/’unlocked’ individually by using #33 with the
CONTROLassigned to the respective output; on T models the AUX settings are also
locked/unlocked when Output 1 is locked/unlocked. The settings of all outputs are
locked/unlocked together if #33 is used with CONTROLset to LINK mode.