ZAHNER EL1002 User manual

( )
30/06/2022

Electronic Load

Electronic Load
1 Electronic Load EL1002 ............................................................................ 4
1.1 Packing List.......................................................................................... 4
2 Caution.......................................................................................................5
3 Introduction................................................................................................7
3.1 Modular Concept –Extension to ZENNIUM Series Potentiostat ......7
3.1.1 EL1002 Electronic Load..................................................................7
3.1.2 EPC42 Controller Card...................................................................8
3.2 Stand-Alone Mode ............................................................................. 9
4 Operation Basics......................................................................................10
4.1 Signals & Connections.......................................................................10
4.1.1 Conductor Rails ..............................................................................11
4.1.2 Safety Interlock............................................................................. 12
4.1.3 Signal LEDs & Buzzer ................................................................... 12
4.2 Operation Steps ................................................................................13
5 Thales Software.......................................................................................15
6 Cell Connection Fundamentals...............................................................19
6.1 Contact Resistance............................................................................19
6.2 4-Electrode Cell Connection Scheme............................................. 20
6.3 Two-Electrode Cell Connection Scheme.........................................21
6.4 Parasitic Inductances....................................................................... 22
7 Connection Configurations .................................................................... 25
7.1 Applications for the EL1002 without external devices.................... 26
7.1.1 Full cell configuration (Standard Kelvin Scheme) .....................26
7.1.2 Half-cell configuration –Cathode...............................................27
7.1.3 Half-cell configuration –Anode ..................................................27
7.1.4 Partial cell configuration ..............................................................28

Electronic Load
7.2 General notes for applications with external supply or load.......... 29
7.3 Applications with an additional DC load...........................................31
7.3.1 DUT connected to the EL1002 with an additional DC load
using the EXT+ terminal ........................................................................ 31
7.3.2 DUT connected to the EL1002 with a parallel DC load.......... 32
7.4 Applications with an additional power supply in series.................. 34
7.4.1 Charging batteries ....................................................................... 34
7.4.2 Electrolysis of fuel cells.............................................................. 36
7.4.3 Compensation for voltage drop (Zero Volt Option).................37
7.5 Applications with an additional power supply in parallel using the
EXT+ terminal.......................................................................................... 39
7.5.1 Charging........................................................................................ 40
7.5.2 Discharging ................................................................................... 41
7.5.3 State of charge (SoC)..................................................................42
7.5.4 Summary parallel power supply with PAD4............................. 43
8 Specifications ......................................................................................... 44
8.1 Ranges and tolerances..................................................................... 44
8.2 General specifications...................................................................... 45
8.3 Safe operation conditions................................................................ 46

Electronic Load -4-
1Electronic Load EL1002
Zahner products are carefully manufactured, calibrated and tested to ensure our
high-quality standard. Packing of the electronic load EL1002 and accessories is
done with great care to avoid damage during transport. Upon receipt of the Zahner
shipment, please check the device and accessories to make sure they are intact. If
a product is damaged during shipment, please immediately contact your Zahner’s
service partner.
1.1 Packing List
EL1002
EPC42 cable
Sense cable (Lemosa plug to blue & green twisted cables)
USB cable
Power cord
USB Stick:
oCalibration report
oCalibration data
oThis manual (pdf)
Zahner Analysis license key
This manual

Electronic Load -5-
2Caution
Please read the risk assessment document before operating the potentiostat.
Prevent the inputs of the potentiostat from electrostatic discharge (ESD)! ESD may
damage the potentiostat. ESD-related damages are not covered by the warranty of
the potentiostat. The user must make sure to discharge his-/herself from any
electrical charge before touching the potentiostat (TIP: use grounded ESD-matts).
Zahner’s potentiostats require a warm-up time of 30 minutes for optimum
performance.
Do not connect active objects such as batteries or fuel cells to the power outputs
of the potentiostat when the potentiostat is switched off! This may damage the
potentiostat.
To drive high currents with the EL1002, the customer must use a cable
recommended for high current applications and fix it to the terminals with suitable
cable lugs.
Pay attention to the wire connections and strictly follow the guidelines of this
manual. Accidentally reversed polarity may damage your device.
During operation the potential on the positive (+) terminal of the EL1002 should be
at least 1 V higher than the negative (–) terminal.
Always turn ON the EL1002 after turning on the external load or external power
supply.
No current should flow through the electronic load immediately after turning on the
electronic load, before the the startup calibration is finished.
Always turn OFF the EL1002 prior to the external load or external power supply.
Properly connect the EPC42 cable with the electronic load by using screws.
Accidental unplugging of the EPC42 cable during operation may damage your
device.
When working with high currents, remove all metallic jewelry/watches which can
possibly create short circuits.

Electronic Load -6-
Don’t touch the electrical connections during operation.
Never apply potentials exceeding 100 V using the EL1002.
The maximum current through the positive (+) terminal of EL1002 must never
exceed 200 A.
The maximum current through the shunt/current measurement unit of the EL1002
must never exceed 680 A.
The cables must be as short and thick as possible.
During EL1002 start up and calibration, do not sink external DC current.

Electronic Load -7-
3Introduction
Zahner’s electronic load EL1002 can be used as an extension to the ZENNIUM
series potentiostats or in a stand-alone configuration. In the following sections,
both scenarios are discussed.
3.1 Modular Concept –Extension to ZENNIUM Series Potentiostat
3.1.1 EL1002 Electronic Load
Dynamic measurements (e.g. impedance spectroscopy) on electrochemical objects
is a topic of high interest in the field of electrochemistry. Modern EIS instruments
cover a broad frequency range from µHz to MHz and can handle impedances
ranging from µΩ to GΩ. However, the maximum applied current is mostly limited to
a few amperes. For many applications in the field of batteries and fuel cells,
measurements at high currents are desired. For the ZENNIUM series potentiostats,
the current range can be significantly extended using Zahner’s electronic load
EL1002.
The EL1002 is a single quadrant potentiostat (it can sink but cannot source current)
and is designed to be used as an extension of the ZENNIUM potentiostat to
investigate high power electrochemical systems. The highly dynamic EL1002 load
is optimized for galvanostatic EIS measurements up to 100 kHz on energy storage
and conversion devices such as proton-exchange membrane (PEM) and solid oxide
(SO) fuel cells.
The EL1002 allows for power dissipation of up to 1 kW in terms of voltages up to
100 V and currents up to 200 A. In combination with a third-party instrument
(electronic loads or sources), measurements at higher currents (up to 680 A) can
be carried out. Moreover, the EL1002 setup can be combined in different ways with
power supplies to allow for measurements on electrolyzers and large format
batteries.
Equipping our Zennium workstation setup with our parallel measurement channel
cards (PAD4) upgrades the EL1002 to the optimal instrument for all kinds of stack
measurements on batteries, fuel cells and electrolyzers. For the connection of the
EL1002 with the ZENNIUM potentiostat, an EPC42 interface card is used.

Electronic Load -8-
3.1.2 EPC42 Controller Card
An EPC42 card has 4 connection ports by which up to 4 power potentiostats
(PP2X2 and/or XPOT2) or electronic loads (EL1002) can be connected. Up to four
EPC42 cards can be installed in a ZENNIUM series potentiostats. Therefore, a total
of up to 16 external devices (PP2X2, XPOT2, EL1002) can be connected to a
ZENNIUM series potentiostat with four EPC42 cards.
Each port of the EPC42 card provides analogue and digital interfaces for the
communication between the electronic load and the ZENNIUM potentiostat. The
analogue part of the port feeds the electronic load with a signal which dictates DC
voltage as well as AC amplitude at a resolution of 16 bit. The current and voltage
signals measured by the electronic load are forwarded via the digital part of the
port to the ZENNIUM, where they are processed in the same way as the signals
from the internal cards. This means the signals are quantized with up to 32 bits.
The EPC42 card provides a bandwidth of 250 kHz.
A bi-directional serial communication line allows to digitally control the external
potentiostat functions and measuring ranges.
External power potentiostats or loads connected to the ZENNIUM series
potentiostats can only be operated sequentially. Simultaneously controlling
multiple power potentiostats is not possible.
Never plug or unplug the D-SUB connector at the backside of the electronic load
while the ZENNIUM is switched on. Otherwise, the devices and the object may be
damaged. It is recommended to fix the D-SUB connector with the screws to
prevent accidental unplugging.

Electronic Load -9-
3.2 Stand-Alone Mode
Zahner’s power potentiostats or electronic loads (PP2X2, XPOT2, EL1002) can also
be operated in stand-alone mode, for which a Windows 10/11 or Linux computer is
necessary. For software updates, Windows 10/11 is required and the use of a virtual
machine is not permitted. The application of a USB hub for connecting the device
is not recommended.
The potentiostats are controlled in stand-alone mode by the Zahner-Lab. In stand-
alone mode, DC measurements are possible (charging/discharging experiments,
constant current/potential).
The PP2X2/XPOT2/EL1002 potentiostat can also be controlled with other third-
party software (e.g., Python, and C++). This allows for the integration in already
established experimental setups. The potentiostats provide serial interfaces via
two USB serial ports which can be used to communicate with the potentiostat via
the SCPI protocol.
In the future, it is planned that the ethernet interface will be activated via a free
software update.
Zahner has prepared a GitHub library for controlling the PP2X2/XPOT2/EL1002
potentiostats with Python via SCPI:
https://github.com/Zahner-elektrik/zahner_potentiostat
And a GitHub repository with examples using the library:
https://github.com/Zahner-elektrik/Zahner-Remote-Python
The API documentation can be found at:
https://doc.zahner.de/zahner_potentiostat

Electronic Load -10-
4Operation Basics
The EL1002 external electronic load is a one quadrant potentiostat. This means
that it can sink (but cannot source) current in a fixed, given polarity. Hence, when
the EL1002 is connected to a battery, it can only discharge the battery, while
charging is not possible without a third-party source.
Typical applications of the EL1002 are discharging experiments at (rechargeable)
batteries and fuel cells. The EL1002 can be operated in both potentiostatic and
galvanostatic modes, controlled by the Thales software. For low impedance
objects such as batteries and fuel cells, the galvanostatic mode is highly
recommended, and the impedance measurement is also optimized for this mode.
4.1 Signals & Connections
Fig. 1: EL1002 front
Fig. 2: EL1002 back

Electronic Load -11-
4.1.1 Conductor Rails
The EL1002 copper rails feature M10 screw threads for proper mounting of the
cables. The screws can be tightened with a maximum torque of 47 Nm,
corresponding to the torque of screws with a strength class of 8.8. The screws
must be driven through the entire copper rail (15 mm thread depth in the copper). It
is recommended to use screws with a strength class of 8.8 and a length exceeding
15 mm, depending on the thickness of the cable lug.
For simplification, we will distinguish the current between the +and –terminals of
EL1002 with Iand current between EXT+ and –terminals of EL1002 with i.
EL1002 has three terminals at the backside of the device labeled as positive (+),
negative (-) and external positive (EXT+) terminals. The device only allows current
(I) flow into one direction from the +to the –terminal. This means that a device
under test (DUT, e.g.,a battery) can only be connected to the EL1002 in one
polarity. Always connect the anode (-) pole of a battery, fuel cell etc. with the
negative (-) terminal of the EL1002 and the cathode (+) to the positive (+) terminal! If
that DUT is connected to the EL1002 using wrong polarity, the polarity error LED
will light up. However, when the EL1002 is combined with an external power supply
via the EXT+ terminal (see chapter 6), then the current (i) can flow into both
directions between the EXT+ and –terminals.
Fig. 3: EL1002 connection scheme
i
I

Electronic Load -12-
The current I is limited to +200 A (unidirectional, single quadrant, sink).
The current i is limited to ±680 A (bidirectional).
4.1.2 Safety Interlock
The interlock only interrupts the gate voltage (control voltage) of the power
transistors of the current controller. No relay or anything comparable is opened. If
the power transistors are faulty and short-circuited, they cannot be interrupted.
Carefully read the risk assessment document for the operation of the EL1002.
The output stage of the EL1002 can be switched off by a potential-free relay
contact by opening the interlock contact. The cable should be as short as possible
and twisted to avoid interferences. The connection from the copper rails EXT+ to -
is not interrupted when the interlock is opened.
The EL1002 and the software do not recognize whether the interlock is open or
closed.
4.1.3 Signal LEDs & Buzzer
The EL1002 is equipped with various signal and warning LEDs on the front panel as
well as a buzzer.
The status LED lights up green when the CPU of the EL1002 is running and the
device is ready for use. When the CPU is busy with a task or command, the status
LED lights up orange. The active LED lights up green when the power supply of the
device is switched on. When the output stage (current controller) of the EL1002 is
switched on, the LED lights up orange.
The polarity error indicating wrong connection between EL1002 and an active
object is only shown by a LED as warning signal. All other errors such as over-
current or exceeding voltage, power or temperature limits are displayed by LEDs
lighting up above certain threshold values and additional buzzers beeping above a
second set of threshold values.
The warning threshold at which the LEDs start to light up is set at about 95% of the
maximum allowed limits, whereas the buzzer sets in when the limit is exceeded.

Electronic Load -13-
4.2 Operation Steps
1. Turn ON external power supply/load (if it is planned to be used).
2. Turn ON the ZENNIUM device as well as the EL1002 and allow for 15 minutes
of warm-up time.
3. Start the Thales software.
4. Select the EL1002 device in the Test Sampling Window. This will initiate a
calibration procedure of EL1002.
5. Select the desired potential range and reference electrode.
6. Connect the sense cables to the DUT with correct polarity –connect the
blue sense cable to the negative terminal and the green sense cable to the
positive terminal of the DUT.
7. The displayed potentials in the Test Sampling Window must be negative.
8. The potential difference between the positive and negative terminal of
EL1002 must not exceed the selected voltage range of 4 V or 100 V,
respectively (absolute limit: 100 V)
9. Connect the power cables to the DUT (as well as to an external power
supply or load/sink, if necessary) according to the preferred configuration.
10. Connect the PAD4 sensing cables (if required) and choose the PAD4 option
in the Thales software.
11. Select the potentiostatic or galvanostatic mode and turn ON (for low Ohmic
DUT the galvanostatic mode is recommended).
12. Perform the experiment.
13. Turn OFF the potentiostat/galvanostat.
14.Shut down the Thales software.
15. Turn OFF the EL1002 and ZENNIUM.
16. Turn OFF the external power supply/load.
17. Remove all the cables (sense and power cables).
If the external power supply is required to supply the DUT, skip the last two steps.
Making sure the correct polarity, the DUT may be connected to the EL1002
potentiostat in one of the different ways described in the next sections.

Electronic Load -14-
⚠️Do not sink external DC current during EL1002 start up and calibration. No
current is allowed to flow through the current measuring device, otherwise it will be
calibrated as an offset.

Electronic Load -15-
5Thales Software
The EL1002 requires Thales version 5.8.3 or later.
All external potentiostats are directly controlled by the Thales software. In Thales,
each device has a unique device number which is identical to the EPC42 port
number to which the external potentiostat is connected, if no RMUX card is
installed. For example, if a device is connected to EPC port 3, then in Thales the
device is addressed as “device number 3”. Device number 0 is reserved for the
internal main potentiostat of the ZENNIUM series potentiostat.
If a RMUX (relay multiplexer) card is installed in a ZENNIUM series potentiostat,
then the 16 device numbers (per RMUX card) are assigned to the RMUX channels.
Hence, if one RMUX card is installed, the device numbers 1-16 are assigned to the
RMUX channels. Similarly, if 2 RMUX cards are installed, the device numbers 1-32
are assigned to the RMUX channels.
To select a potentiostat in the Thales software, follow these steps:
1. Start the Thales software in the classic mode.
2. Click on the “EIS” icon.
3. Click on “Control potentiostat”.
4. Click on the “DEVICE” button in “Test sampling & control potentiostat”
window.
By clicking on the “DEVICE” button, an input box opens where the user can type in
the device number. After confirming, the device is selected and the type of device
is displayed.
Fig. 4: Selecting an external potentiostat in the test sampling window. DEVICE 1: XPOT2 indicates
that the XPOT2 is connected to the port 1 of the EPC42 card.

Electronic Load -16-
If no device is connected to the selected EPC42 port, an error message is
displayed and the Thales software automatically switches to the internal
potentiostat.
If the selected device is connected, the Thales software automatically starts the
start-up calibration routine of the external potentiostats upon selection.
Thales outputs an error message if no calibration data is found for the device and a
question mark (?) is displayed after the calibration button on the GUI.
Fig. 5: Testsampling page
Connect the blue sense cable to the negative (–) terminal and the green sense
cable to the positive (+) terminal of the DUT. This will lead to correct polarity
display and a negative potential in the DC VOLTAGE window.
When the mouse cursor hovers above a button or input box and the item is
highlighted, the current and voltage displays are not updated.

Electronic Load -17-
Fig. 6: Check Cell Connections page
In “check cell connections”you can set the desired potential range (4 V / 100 V)
and choose a reference electrode. For convenience, the EL1002 connection
scheme with the third-party DC load is shown here.
Now connect the sense cables from the EL1002 to the DUT. Here, a battery is used
as DUT. Thereafter, connect the power cables used for the desired EL1002
arrangement. Please note that by connecting the power cables, the potential must
not change considerably (connect power cables as shown for your preferred
arrangement in the manual below).

Electronic Load -18-
When the DUT is connected correctly, the voltage is negative and the current
flowing into the EL1002 is positive.
When changing the device number, the now unselected external potentiostat will
hold its DC conditions such as DC potential or current and its on/off status until the
settings are changed again
Voltage and current outputs of the unselected external potentiostat are not
measured and are not monitored for defined voltage/current limits.
Only the selected external potentiostat is internally connected to the FRA of the
ZENNIUM series potentiostat. Therefore, only the active external potentiostat can
output an AC signal.

Electronic Load -19-
6Cell Connection Fundamentals
All Zahner’s measuring instruments follow the same 4-electrode cell connection
scheme, which is also referred to as 4-terminal sensing or Kelvin connection. This
includes connections to the working electrode (copper rail denoted with -), working
electrode sense (WES), reference electrode (RE), and counter electrode (copper
rail denoted with +). These connections are specified by their color code, with
WES: blue and RE: green, while the copper rails are labelled on the rear panel. To
minimize interference due to stray- and mutual inductance, the power cables
(current-carrying cables) should be twisted around each other on the highest-
possible length, and moreover, the green and blue sense cables should also be
twisted. Twisting is not depicted in the schematic below.
Fig. 7: 4-electrode connection scheme. The current is conducted through the black (WE) and red
(CE) wires. The voltage is measured between the green (RE) and blue (WES) wires.
For high current flow, the 4-electrode connection scheme is highly recommended
to minimize the error margin in the measurement, especially when using the
EL1002.
6.1 Contact Resistance
Fig. 8 shows a typical electrical wire connection between the potentiostat and the
test object. The resistance of the wire can be divided into two parts being the wire
resistance and the contact resistance.
Fig. 8: Typical electrical wire used to contact potentiostat with the test object. Resistance of the
electrical wire is divided into two different parts. 1) contact resistance Zcontact and 2) wire resistance
Zwire.