Thurlby Thandar Instruments ELP302P Service Manual [en, de, it]

EL302P

Bench Power Supply

INSTRUCTION MANUAL

Table of Contents

Introduction 1
Specification 2
EMC 5
Safety 6
Installation 7
Connections 8
Operation 8
Remote Operation 9
Remote Commands 11
Maintenance 12
Instructions en Francais 13
Bedienungsanleitung auf Deutsch 21
Istruzioni in Italiano 29
Instrucciones en Español 37

Introduction

The EL302P is a digitally controlled version of the standard EL302 linear power supply with an
isolated RS-232 interface.

It offers a low-cost solution for a bas ic programmable PSU, and will be sufficient for many
applications where the sophistication and complexity of GPIB is not needed.

A simple command set allows remote control of voltage, current and output enable together with
read-back of meter ing values and operat ional status.

Local control is via three rotary encoders providing rapid and accurate setting of voltage and
current during bench use.

Excellent line and load regulation is matched by very low noise and good transient response.
Improved power efficiency ensures that the units require no fan cooling.

The EL series has been designed to meet the stringent requirements of relevant IEC standards
for safety and EMC. All outputs are intrinsically short circuit proof and are protected ag ainst
external voltages and reverse currents.

1

Voltage Range:

0V to 30V minimum.

Current Range:

0.01A to 2A minimum.

Resolution 10mV. Sett ing accuracy 0.3% ± 20mV (for V >0.1V)

Resolution 10mA. Setting accuracy 0.6% ± 20mV ( for I >0.1A)

cross-over.

Output Switch:

Electronic. Preset voltage and current displayed when off.

3A.

Load Regulation:

<0.01% of maximum output for 90% load change.

Line Regulation:

<0.01% of maximum output for 10% line change.

(20MHz bandwidth)

Transient Load Response:

<20µs to within 50mV of set level for a 5% to 95% load change.

Temperature Coeff icient :

Typically < 100ppm /°C

Status Indication:

Output on lamp. CC mode lamp.

14mm (0.56") LED displays. Reading rate 4/sec.

100mV and when in CC mode the last digit will be set to zero.

Current (CV mode) 0.6% ± 20mA.

Specification

General specifications apply for the tem per ature 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

Voltage Setting: By coarse and fine rotary encoders or RS-232 interface.

Current Setting: By single rotary encoder or RS-232 interface.

Operating Mode: Constant voltage (CV) or constant current (CC) with automatic

Output Protection: Outputs will withstand forward voltages of up to 20V above the rated

output voltage. Reverse protection by diode clamp for currents up t o

Ripple & Noise:

Typically < 1m Vrms (CV mode).

METER SPECIFICATIONS

Meter Types: Separate 4 digit meter for voltage and 3 digit m et er for current with

Meter Resolutions: 100mV, 10mA

Note that in constant voltage mode the meter will show the set voltage
to resolution of 10mV. However the metering resolution is limited to

Meter Accuracies: Voltage (CC mode) 0.3% ± 100mV.

MEMORY

The power supply saves the voltage, current and output-enable status at power down and restores
the settings at power up.

2

9-pin D connector.

Baud Rate:

Variable from 600 baud to 9,600 baud.

Read Current, Read On/Off, Read Mode (CV or CC).

Current 0.6% ± 20mA (for I >0.1A).

Setting Resolution:

Voltage 10mV. Curr ent 10mA.

Readback Accuracy:

Voltage 0.3% ± 100mV. Current 0.6% ± 20mA.

Readback Resolution:

Voltage 100mV. Curr ent 10mA.

Output T erminals:

Universal 4mm safety binding posts on 19m m ( 0. 75”) pitch.

AC Input:

230V AC or 115VAC ± 10%, 50/60Hz. Installation Category II.

Power Consumption:

160VA 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.

Safety:

Complies with EN61010-1.

EMC:

Complies with EN61326.

Size:

140 x 160 x 295 mm (WxHxD)

Weight:

4.1kg.

RS-232 CONTROL

Interface: RS-232 interface, fully opto-isolat ed from power supply output.

Remote Functions: Set Voltage, Set Current, Set O utput On/Off, Read Voltage,

Setting Accuracy: Voltage 0.3% ± 20mV (for V >0.1V).

GENERAL

3

Performance levels achieved are detailed in the user manual.

EC Declaration of Conformity

We Thurlby Thandar Instruments Ltd
Glebe Road
Huntingdon
Cambridgeshire PE29 7DR
England

declare that the

EL302P Bench Power Supply

meets 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 Comm unit ies.

EMC

Emissions: a) EN61326-1 (2006) Radiated, Class B

b) EN61326-1 (2006) Conducted, Class B
c) EN61326-1 (2006) Harmonics, referring t o EN61000-3-2 (2006)

Immunity: EN61326-1 (2006) Immunity Table 1, referring t o:

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

Safety
EN61010-1 Installation Category II, Pollution Degree 2.

CHRIS W ILDING
TECHNICAL DIRECTOR

2 January 2013

4

This instrument has been designed to meet the requirements of t he EMC Directive 2004/108/EC.
Compliance was demonstrated by meeting the test limits of t he 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 B
b) Conducted: Class B
c) Harm onics: 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 per formance achieved are shown below (requirement shown in
brackets):

a) EN61000-4-2 (2009) Electrostatic Discharge : 4k V air, 4kV contact, Perfor m anc e A (B).

EMC

b) EN61000-4-3 (2006) Electromagnetic Fie ld:

3V/m, 80% AM at 1kHz, 80MHz – 1GHz: Performance A ( 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 B (B);

25 cycles, 70% and 250 cycles, 0%: Performance B (C) .

d) EN61000-4-4 (2004) Fast Transient, 1kV peak (AC line), 0·5kV peak ( DC Out puts) ,
Performance B (B).

e) EN61000-4-5 (2006) Surge, 0·5kV (line t o line), 1kV (line to ground), Perform ance A (B).
f) EN61000-4-6 (2009) Conducted RF, 3V, 80% AM at 1kHz (AC line only; DC Output

connections <3m, therefor e not tested), Performance A (A).
According to EN61326-1 the definitions of performance criteria are:

Performance criterion A: ‘During test normal performance within the specificat io n limits.’
Performance criterion B: ‘During t est , temporary degradation, or loss of function or

performance which is self-recovering’.
Performance criterion C: ‘During t est, temporary degradation, or loss of function or

performance which requires operat or int er vention or s ystem r eset occurs.’
Where Performance B is stated it is because DC Output regulation, or V & I measurement

accuracy, m ay deviate beyond Specification limits under the test conditions. However, the
possible deviations are still small and unlikely to be a problem in practice.

Note that if operation in a high RF f ield is unavoidable it is good pract ice t o c onnect 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 connect ions ar e

remade correctly and that case screws are corr ect ly refitted and tightened.

b) In the event of part replacement becoming necessary, only use components of an identical

type, see the Service Manual.

5

l

Safety

This power supply is a Safety Class I instrument according to IEC classification and has been
designed to meet the requirem ents of EN61010-1 (Safety Requirements for Elect r ical Eq uipment
for Measurement, Control and Laborator y Use). It is an Installation Category II instrument
intended for operation from a normal single phase supply.

This instrument has been tested in accordanc e 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 r etain the inst r um ent in a safe condition.

This instrument has been designed f or 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 spec ified by these instructions may impair the safety
protection provided. Do not operate the instrum ent outside its rat ed supply voltages or
environmental range.

WARNING! THIS INSTRUMENT MUST BE EARTHED

Any interruption of the mains earth conduct or inside or outside t he inst r um ent will make the
instrument dangerous. Int entional 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, t er minals 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, m aint enance 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 1 minute 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 def ec t ive, has been subj ec t t o 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 f or
replacement. The use of makeshift fuses and the short-circuiting of fuse holders is prohibited.

Do not wet the instrument when cleaning it. The following symbols are used on the instrument
and in this manual:-

Earth (ground) terminal.

mains supply OFF

mains supply ON
alternating current (ac)

direct current (dc)

6

Mains Operating Voltage

Check that the instrument oper ating 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. Ensure that the instrument is disconnect ed from the AC supply.

2. Remove the screws holding the case upper and handle and lift off the case upper.

3. Change the transformer c onnections following the diagram below:

230V Operation 115V Operati on

BLUE BROWN BLUE BROWN

Installation

4. Re-assemble in the reverse order.

5. To comply with safety standard requirem ents t he oper at ing voltage marked on the rear panel
must be changed to clearly show the new voltage setting.

Fuse

The AC 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 f use dr awer with a suitable tool.

The correct fuse type is 20 x 5mm 250V HBC time-lag with the following rating:

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.

Mains Lead

When a three c or e m ains lead with bare ends is provided this should be connect ed as follows:

As the colours of the wires in the mains lead of this apparatus m ay not cor r es pond with the
coloured markings identifying the terminals in your plug proceed as follows:

230V operation : 1.6A (T)
115V operat ion: 3.15A (T)

BROWN - MAINS LIVE
BLUE - MAINS NEUTRAL

GREEN/YELLOW - EARTH Safety Earth Symbol

The wire which is coloured green-and-yellow must be connected to the terminal in the plug which
is marked by the letter E or by the safety earth symbol shown above or coloured green or green­and-yellow.

The wire which is coloured blue must be connected to the terminal which is marked with the letter
N or coloured black.

The wire which is coloured brown must be connected to the terminal which is marked with the
letter L or coloured red.

WARNING! THIS INSTRUMENT MUST BE EARTHED.

Any interruption of the mains earth conduct or inside or outside t he inst r um ent will make the
instrument dangerous. Int entional interruption is prohibited.

7

Pin

Name

Description

1

DCD

Linked to pins 4 and 6

2

TXD

Transmitted data from instrument

3

RXD

Received data to instrument

4

DTR

Linked to pins 1 and 6

5

GND

Signal ground

6

DSR

Linked to pins 1 and 4

7

RTS

Linked to pin 8

8

CTS

Linked to pin 7

9

–

No internal connection

Output Terminals

All power connections are made from the fr ont panel.
The load should be connected to the positive (red) and negat ive (black ) terminals marked

OUTPUT. Both are fully floating and either can be connected to ground.

Connections

The terminal marked

is connected to the chassis and safety eart h ground.

RS232

9–pin D–connector for PC remote control with the following connections:

Connect to a PC with a cable which has pins 2, 3 and 5 wired plus pins 1, 4 & 6 and pins 7 & 8
linked at the PC end.

Setting Up the Output

With the PO WER switch on (l) and the output off the out put voltage and cur r ent limit can be
accurately preset using the VOLTAGE and CURRENT controls; the left-hand met er shows the set
voltage and the right-hand meter shows the set maximum c ur r ent.

When the output switch is switched on, the ON lamp lig hts; the left-hand meter still shows the
preset voltage but the right-hand met er now shows the actual load current.

Constant Voltage

The output voltage is adjusted using the coar se and fine VOLTAGE controls; the coarse control
changes the voltage in 100mV steps and the fine control in 10mV steps. The CURRENT control
sets the maximum current that can be supplied; the c ont r ol changes the current limit in 10mA
steps.

Constant Current

If the load resistance is low enough such that, at t he output voltage set, a current greater than
the current limit setting would flow, the power supply will automatically move into constant current
operation. The current output is adjusted by the CURRENT control and the VOLTAGE controls
set the maximum voltage that can be generated.

The CC lamp lights to show constant current mode.

Instantaneous Current Output

The current limit control can be set t o limit the continuous output current to levels down to 10mA.
However, in com m on with all precision bench power supplies, a capacitor is connected acr os s
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 set ting.

Operation

8

Efficiency

To improve efficiency at low output levels the overhead voltage to the output regulators is
automatically switched by a relay to a lower voltage; hysteresis at the threshold point prevents
unnecessary switching when the output voltage is set at about that level. Apart from an audible
‘click’ the user will be unaware that the relay has switched; there will be no disturbance on the
output.

Protection

The output has intrinsic short-cir cuit pr ot ec t ion and is pr ot ec t ed from reverse voltages by a diode;
the continuous reverse current must not exceed 3 Amps, although transients can be much higher.

In common with all series regulated single-ended power supplies, the unit is not c apable of
sinking current provided fr om an exter nal sour ce.

If a voltage greater than t he set output voltage of the unit is applied from an external source, the
internal regulator will turn off, no current will flow, and the voltage met er will read the applied
voltage. No damage will result providing the applied voltage does not exceed the maximum
output voltage of the power supply by more than 20 Volts. Application of a voltage g reater than
this is prohibited.

Series or Parallel Connection with Other Outputs

The outputs of the power supply are fully floating and m ay be used in series with other power
supply units to generate high DC voltages up to 300V DC.

The maximum permissible voltage between any terminal and earth ground (
maximum permissible voltage between either terminal of one output and any term inal of another
output on the same supply is also 300VDC.

WARNING! Such voltages are exceedingly hazardous and great care should be taken to shield
the output terminals for s uch use. On no account should the output terminals be touched when
the unit is switched on under such use. All connections to the terminals must be made with the
power switched off on all units.

It should be noted that the unit can only source current and cannot sink it, thus units cannot be
series connected in anti-phase.

The unit can be connected in parallel with others to produce higher currents. Where several units
are connected in parallel, the output voltage will be equal to that of the unit with the hig hest
output voltage setting until the current dr awn exceeds its current limit setting, upon which the
output will fall to that of the next highest setting, and so on. In constant current m ode, units can
be connected in parallel to provide a current equal to the sum of t he c ur r ent limit s et t ings.

Ventilation

The power supply can generate significant heat at full power. The supply relies on convection
cooling only and it is therefore important that ventilation is never restricted if performance and
safety are to be maintained.

) is 300VDC; the

Remote Operation

Remote command format and the remote commands themselves are detailed in the Remote
Commands chapter.

Baud Rate Selection

The Baud rate is set by pressing the OPT I ON SELECT/OK button until bAUd appears in the
left-hand display; the right-hand display shows the current setting in the form of
Baud etc. Change the Baud rate by pressing the CHANGE butt on to step the rate through all the

possible options. When t he required rate is displayed press OPTION SELECT/OK ag ain t o
confirm and exit the rate change m ode.

9

960 for 9600

1

DCD

Linked to pins 4 and 6

2

TXD

Transmitted data from instrument

3

RXD

Received data to instrument

8

CTS

Linked to pin 7

9 - No internal connection

Start Bits: 1

Parity: None

Data Bits: 8

Stop Bits: 1

Remote/Local Operation

At power on the instrument will be in the local state with the Rem (remote) lamp off. When a
command is received the remote state will be entered and the Rem lamp will be turned on. The
rotary Controls are not locked out by this action and the instr um ent will be returned t o t he local
state if they are used; however, if the instrument receives another character f rom the interface,
the remote state will again be entered.

Local operation of the rotary controls, output On/Off switch and CHANGE button can be disabled
by pressing the OPTION SELECT/OK but t on until

right-hand display shows the current sett ing ,
button selects
again to confirm and exit the change m ode.

Local operation can be restored at any time by pressing the O PTION SELECT/OK button; if

on or oFF ; when the required setting is displayed press OPT I ON SELECT/OK

LoCL has been set to oFF the first press of OPTION SELECT/OK returns the instrument to

local control and subsequent presses select the ot her modes as described above.

RS232 Connector

The 9-way D-type serial interface connector is located on the instrument r ear panel. The pin
connections are as shown below:

Pin Name Description

LoCL appears in the left-hand display; the

on or oFF . Alternate presses of the CHANGE

4 DTR Linked to pins 1 and 6
5 GND Signal ground
6 DSR Linked to pins 1 and 4
7 RTS Linked to pin 8

Connect to a PC with a cable which has pins 2, 3, 5, wired plus pins 1, 4, 6 and pins 7 and 8,
linked at the PC end, see diagram.

Baud rate is set as described above; the other interface parameters are fixed as follows:

RS232 Character Set

Any ASCII code can be used. Bit 7 of ASCII codes is ignored, i.e. assumed to be low. No
distinction is made between upper and lower case characters in command mnemonics and t hey
may be freely mixed. The ASCII control codes between 00H and 31H are ignored, except for 0AH
(Line Feed, LF) which is used as a command terminator.

10

<rmt>

<RESPONSE MESSAGE TERMINATOR>, CR followed by LF.

<nr1>

A number with no fractional part, i.e. an integer.

<nr2>

A number in a fixed point format, e.g. 11.52, 3.61, etc.

outside the range of the output an er r or will be generat ed.

outside the range of the output an er r or will be generat ed.

ON

Sets the DC output on.

OFF

Sets the DC output off.

V<nr2><rmt>

the command V? will be V 12.55<rmt>.

I<nr2><rmt>

command I? will be I 1.00<rmt>.

RS232 Remote Com m and Formats

The instrument's input buff er acc epts a sing le com mand (or query) at a time, under interr upt, in a
manner transparent to other instr um ent oper ations. Commands and queries must be sent as
specified in the command list and must be ter m inat ed with the com m and terminator code 0AH
(Line Feed, LF). Note that parameters ar e separat ed from the command header by one space
(20H).

After a command has been sent the contr oller must wait at least 10ms from the command
terminator before the next com mand (or query) is started, to allow the instrument to clear t he
input buffer.

Responses to queries are sent immediately. The controller must wait for the response to a query
before the next command or quer y is sent. The instrument responds to the controller after every
query as specified in the commands list. I n every case a response is t erminated by 0DH
(Carriage Return, CR) followed by 0AH (Line Feed, LF).

<WHITE SPACE> is defined as character codes 00H to 20H inclusive. <WHITE SPACE> is ignor ed

except in command identifiers. e.g. '*I DN?' is not equivalent to '*IDN?'.
The high bit of all characters is ignored.
The commands are case insensitive.

Remote Commands

Command List

This section lists all commands and queries implemented in this instrument. The commands are
listed in alphabetical order within the function groups.

The following nomenclature is used:

Set-up Commands

V <nr2> Set the voltage to <nr2>. The value of <nr2> must be in Volts; no

I <nr2> Set current limit to <nr2>. The value of <nr 2> m us t be in Amps; no

Readback Commands

V? Returns the set output voltage in Volts in <nr2> numeric format.

multipliers are allowed. If the value of <nr2>, af t er rounding, is

multipliers are allowed. If the value of <nr2> , after rounding, is

The syntax of the response is

Example: If the set output voltage is 12.55 Volts the response to

I? Returns the output current limit in Amps in <nr2> numeric format.

The syntax of the response is

Example: If the current limit is 1.00 Amps the response to the

11

<nr2>V<rmt>

response to the command VO? will be V12.55<rmt>.

<nr2>A<rmt>

the command IO? will be A0.93<rmt>.

or OUT OFF<rmt>

or M CC<rmt>

2 = command value outside instrument limits.

(1.00V, 1. 00A, output off).

<version> is the revision level of the software installed.

VO? Reads and returns the actual output voltage in Volts in <nr2>

numeric format. The syntax of the response is

Example: If the actual output voltage is 12.55 Volts the

IO? Reads and returns the actual output curr ent in Amps in the <nr2>

numeric format. The syntax of the response is

Example: If the output current is 0. 93 Amps the response to

OUT? Returns status of the output as

OUT ON<rmt>

M? Returns output mode status as

M CV<rmt>

ERR? Returns the value in the error register in t he form ERR <nr1><rmt>

Miscellaneous Commands

*RST Resets the instrument to the default power-up settings

*IDN? Returns the instrument identification. The exact response is

The Manufacturers or their ag ents overseas will provide repair for any unit developing a fault.
Where owners wish to undertake t heir own maintenance work , this should only be done by skilled
personnel in conjunction with the service manual which may be purchased directly from the
Manufacturers or their agents overseas.

0 = no errors.
1 = command not recognised.

determined by the instrument configuration and is of the form
<NAME>,<model>, 0, <version><rmt> where <NAME> is the
manufacturer's name, <model> defines the type of instrument and

Maintenance

Cleaning

If the PSU requires cleaning use a clot h t hat is only lightly dampened with water or a mild
detergent. Polish the display window with a soft dry cloth.

WARNING! TO AVOID ELECTRIC SHOCK, OR DAMAGE TO THE PSU, NEV ER ALLOW
WATER TO GET INSIDE THE CASE. TO AVOID DAMAGE TO THE CASE OR DISPLAY
WINDOW NEVER CLEAN WITH SOLVENTS.

12

courant alternatif (c.a.)

Sécurité

Cet instrument est de Classe de sécurité 1 suivant la classif icat ion I EC et il a été c onst ruit pour
satisfaire aux impératifs EN61010-1 ( impér atifs de sécurité pour le matériel électrique en vue de
mesure, commande et utilisation en laboratoire) . Il s'agit d'un instrument d'installation Catég orie
II devant être exploité depuis une alimentation monophasée habituelle.

Cet instrument a été soumis à des essais conformément à EN61010-1 et il a été fourni en tout
état de sécurité. Ce manuel d'instructions contient des informations et avertissements qui doivent
être suivis par l'utilisateur afin d'assurer un fonctionnement de toute sécurité et de conserver
l'instrument dans un état de bonne sécurité.

Cet instrument a été conçu pour être ut ilisé en inter ne dans un environnement de pollution
Degré 2, plage de températur es 5°C à 40°C, 20% - 80% HR (sans condensation). Il peut être
soumis de temps à autre à des températures c om pr ises entre +5°C et -10°C sans dégradation
de sa sécurité. Ne pas l'utiliser lorsqu'il y a de la condensation.

Toute utilisation de cet instr um ent de m anièr e non spéc ifiée par ces instructions risque d'affecter
la protection de sécurité conférée. Ne pas utiliser l'instrument à l'extérieur des tensions
d'alimentation nominales ou de la gamme des conditions ambiantes spécifiées.

AVERTISSEMENT! CET INSTRUMENT DOIT ETRE RELIE A LA TERRE

Toute interruption du conducteur de terre secteur à l'intérieur ou à l'extérieur de l' inst r ument
rendra l'instrument dangereux. I l est abs olument interdit d'effectuer une interrupt ion à dessein.
Ne pas utiliser de cordon de prolongation sans conducteur de protect i on, c ar cec i annulerait sa
capacité de protection.

Lorsque l'instrument est r elié au sect eur, il est possible que les bornes soient sous tension et par
suite, l'ouverture des couvercles ou la dépose de pièces (à l'exception de celles auxquelles on
peut accéder manuellement) risque de mettre à découvert des pièces sous tension. Il faut
débrancher ke cordon secteur de l'appareil avant de l'ouvrir pour effectuer des réglages,
remplacements, travaux d'entretien ou de réparations. Les condens at eur s qui se trouvent dans le
bloc d'alimentation risquent de rester chargés, même si le bloc d'alimentation a été déconnecté
de toutes les sources de tension, mais ils se décharg er ont en toute sécurité environ 10 minutes
après extinction de l'alimentation.

Eviter dans la mesure du possible d'effectuer des rég lages, travaux de réparations ou d'entretien
lorsque l'instrument ouvert est br anc hé au secteur, mais si c'est absolument nécessaire, seul un
technicien compétent au courant des risques encour us doit effectuer ce genre de travaux.

S'il est évident que l'instrument est défectueux, qu'il a été soumis à des dégâts mécaniques, à
une humidité excessive ou à une corrosion chimique, la protection de sécurité ser a am oindr ie et
il faut retirer l'appareil, afin q u'il ne soit pas utilisé, et le renvoyer en vue de vérifications et de
réparations.

Remplacer les fusibles uniquement par des fusibles d' int ensit é nom inale requise et de type
spécifié. Il est interdit d'ut iliser des fusibles bricolés et de court-circuiter des port e-fusibles.
Eviter de mouiller l'instrument lors de son nettoyage.
Les symboles suivants se trouvent sur l'instrument, ainsi que dans ce m anuel.

Borne de terre (masse)

l

13

alimentation secteur ON (allumée)
alimentation secteur OFF (éteinte)

courant continu (c.c.)