Thurlby Thandar Instruments EB2025T User Manual [en, de, fr, it]

EB2025T

Triple Power Supply

INSTRUCTION MANUAL

Introduction

The EB2025T is a general purpose bench power supply intended for applications requiring stable
and controllable sources of DC voltage at low cost. Thr ee independent and fully isolated outputs
are provided.

Output A is a fixed 5 Volt output with a maximum current capability of 1 Amp and full short circuit
protection.

Outputs B and C are independently adjustable up t o 20 Volts with a maximum current capability of
250 milliamps each. The built–in analogue meter can be set to measure voltage or current for
either of these outputs.

Outputs B and C also offer fully variable control of the current limit point. This can be used to
provide over–current protection for delicate circuits. Alternatively the outputs can be used as
constant current sources with automatic crossover between constant voltage and constant current
operation. The outputs can operate continuously into a short circuit at maximum current setting.

Because they are fully isolated, outputs B and C can be externally connected either in series or in
parallel to provide voltages up to 40 Volts or currents up to 500 milliamps.

All three outputs are fully protected against accidental connection of reverse voltages.

Table of Contents

Introduction 1
Specification 2
Safety 4
EMC 5
Installation 6
Operation – Main Outputs 6
Operation – Logic Output 7
Operation – General 8
Maintenance 8
Instructions en Francais 9
Bedienungsanleitung auf Deutsch 13
Istruzioni in Italiano 17
Instrucciones en Español 21

1

Voltage Range:

0.3V to 20V minimum.

Current Range:

1mA to 250mA minimum.

Voltage Setting:

By single linear control.

Current Setting:

By front panel screwdriver adjustment.

Operating Mode:

Constant voltage or constant current with automatic cross–over.

diode clamp for currents up to 1A.

Load Regulation:

<0.2% of maximum output for 90% load change.

Line Regulation:

<0.1% of maximum output for 10% line change.

Ripple:

<2mV rms

Meter Accuracy:

± 5% of reading ± 0.5% of full–scale.

Voltage:

5V ± 0.2V

Current Limit:

1A minimum.

protection for currents up to 1A.

Ripple:

<2mV rms.

Load Regulation:

<2% for a 90% load change.

Line Regulation:

<0.2% for a 10% line change.

Status Indication:

Overload lamp (current >1 Amp).

Output T e rminals:

4mm terminals on 19mm (0.75") pitch.

AC Input:

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

Power Consumption:

50VA max.

Operating Range:

+5°C to +40°C, 20% to 80% RH.

Storage Range:

–40°C to +70°C.

Environmental:

Indoor use at altitudes up to 2000m, Pollution Degree 2.

Safety:

Complies with EN61010–1.

EMC:

Complies with EN61326.

Size:

220 x 82 x 230mm.

Weight:

1.8 kg.

MAIN OUTPUTS

Output Protection: Outputs will withstand forward voltages up to 30V. Reverse protection by

LOGIC OUTPUT

Specification

Output Protection: Output will withstand up to 16V forward voltage. Diode clamp reverse

GENERAL

2

Performance levels achieved are detailed in the user manual.

EC Declaration of Conformi ty

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

declare that the

EB2025T 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 Communities.

EMC

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

b) EN61326-1 (2006) Conducted, Class B
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

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

CHRIS WILDING
TECHNICAL DIRECTOR

2 January 2013

3

l

alternating current (ac)

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 war nings 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 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 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.

4

mains supply ON.

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 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 performance achieved are shown below (requirement shown in
brackets):

a) EN61000-4-2 (2009) Electrostatic Discharge : 4kV air, 4kV contact, Performance A (B).

EMC

b) EN61000-4-3 (2006) Electromagnetic Field:

3V/m, 80% AM at 1kHz, 80MHz – 1G Hz: Perf ormance B

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%: Performance B (C); 250 cycles, 0%: Performance B (C).

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

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

connections <3m, therefore not tested), Performance B



minor voltage regulation and current measurement deviation at some frequencies.

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 f unction 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.’
Where Performance B is stated it is because DC Output regulation may deviate beyond

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



(A) and



(A).

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 pas sed (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.

5

Mains Operating Voltage

Check that the instrument operating voltage marked on the rear panel is suitable for the local
supply. The operating voltage is factory set and cannot be changed by the user.

Fuse

The AC fuse is located in the fuse holder on the rear panel.
The correct fuse type is 20 x 5mm 250V HBC time-lag wit h the following rating:

230V: 630mAT
115V: 1.6AT

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

Installation

When a three core mains lead with bare ends is provided this should be connected as follows:

As the colours of the wires in the mains lead of this apparatus may not correspond with the
coloured markings identifying the terminals in your plug proceed as follows:

The wire which is coloured green-and-yellow must be connected to the terminal in the 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.

Any interruption of the mains earth conductor inside or outside the instrument will make the
instrument dangerous. Intentional interruption is prohibited.

BROWN - MAINS LIVE
BLUE - MAINS NEUTRAL

GREEN/YELLOW - EARTH Safety Earth Symbol

Switching On

Switch on the power supply using the POWER switch on the front panel. To fully disconnect from
the AC supply unplug the mains cord from the back of the instrument or switch off at the AC
supply outlet; make sure that the means of disconnection is readily accessible. Disconnect from
the AC supply when not in use.

WARNING! THIS INSTRUMENT MUST BE EARTHED.

Setting Up the Output

With the POWER switch on the output voltage can be set using the VOLTS control. To monitor
the voltage on the meter select the appropriate output (B or C) on the meter OUTPUT switch and
select V on the meter FUNCTION switch.

The current limit can be adjusted with a small screwdriver through the aperture in the front panel.
To monitor the load current select mA on the meter FUNCTION switch.

6

Operation - Main Outputs

Constant Voltage

The output voltage is adjusted using the VOLTS control; the Current Limit adjustment sets the
maximum current that can be supplied.

Constant Current

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

Instantaneous Current Output

The current limit adjustment can be set to limit the continuous output current to levels down to
1mA. However, in common with all 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.

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. Apar t from an audible
‘click’ the user will be unawar e t hat the relay has switched; there will be no disturbance on the
output.

Protection

The output has intrinsic short-circuit protection and is protected from reverse voltages by a diode;
the continuous reverse current must not exceed 1 Amp, although transients can be much higher.

In common with all series regulated single-ended power supplies, the unit is not capable of
sinking current provided from an external source.

If a voltage greater than the 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 meter will read the applied
voltage. No damage will result providing the applied voltage does not exceed 30 Volts. Application
of a voltage greater than this is prohibited.

Output Voltage

The output voltage is fixed at 5V ± 0.2V.

Current Limit

The output will go into current limit above 1A; as the load current is incr eased beyond 1A the
output voltage will start to fall and at about 4.5V the Overload lamp will light.

Protection

Operation - Logic Output

The output has intrinsic short-circuit protection and is protected from reverse voltages by a diode;
the continuous reverse current must not exceed 1 Amp, although transients can be much higher.

The output is protected against external forward voltages up to 16 Volts.

7