FRA-X
Zahner’s IM7 series potentiostats have limited voltage and current ranges (i.e., IM7x: Voltage range ±15 V, Current range: ±4 A). Even with an extension of Zahner’s electronic load (EL1002), the maximum working voltage and current are ±100 V and ±680 A, respectively.
In many applications, electrochemical impedance spectroscopy (EIS) is desired at even higher voltages and/or currents. For these applications, Zahner’s IM7 series potentiostat can be interfaced with an external device (EXD) via an FRA-X, allowing for high currents and voltages only limited by the specs of the external device.
The Zahner Lab software fully supports the FRA-X. It is possible to incorporate the FRA-X in a remote test stand and control the setup via Python or C++.
Packing List
FRA-X
Mains cable
Connection cable set “E/I Probe” to IM7 potentiostats (D-SUB9 to ODU)
Voltage Probe set (70/700 V, 140/1400V) as defined
Connection cable “voltage probe” (D-SUB9 to BNC-female)
USB power adapter (5V) for voltage probe
Current Probe (100 A, 500 A, 1000 A, 2000 A or 6100 A) as defined
Connection cable “current probe” (D-SUB9 to D-SUB9)
Control cable (Regatron G5, H&H PLI, …) as defined
Ring binder
Risk assessment document
Product manual description
Caution
Caution
Please read the risk assessment document before operating the potentiostat.
The FRA-Probe only outputs an analog setpoint signal for the external power device. The configuration and switching on/off of the external power device must be controlled separately by the user.
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.
Properly connect (with screws) the E/I probe cables with the FRA-Probe. An accidental unplugging of the FRA cable during operation may damage your device.
Don’t touch the electrical connections during the operation.
The cables must be as short as possible and as thick as possible.
Requirement of the EXD
An FRA-X setup can be configured to control a third-party source, sink, or source/sink electronic device. The FRA-X acts as an interface and allows IM7/c/x potentiostat to control the output of an external device (EXD). The IM7/c/x potentiostat can use its frequency generator to modulate the output signal of the EXD, so that sine-waves for measuring EIS can be generated, for example.
The EXD must be equipped with an analog control input port for connecting with the FRA-X. The analog control input of the EXD should ideally be in the range of ±10 V or slightly below.
The EXD must be able to operate in galvanostatic (constant current) and potentiostatic (constant voltage) modes to enable EIS measurements in either of these modes. For low-ohmic test objects or high-current measurements, the galvanostatic mode is mostly used and recommended.
When an EXD is interfaced with a IM7/c/x potentiostat via an FRA-X, the IM7 potentiostat works as a controller and thus only the specifications of the EXD and the FRA-X are relevant for the overall system performance. For EIS, it is important to choose an EXD with a fast reaction time (i.e., short rise time).
FRA - EXD Correlation
The internal potential ranges of all IM7 series potentiostats for the FRA application are ±4 V. The FRA-Probe is an interface that connects the IM7 series potentiostats to the EXD. The FRA-Probe works as an amplifier/divider that provides the output/input of the potentiostats to a widely used analogue interface value of ±10 V.
This ±10 V of the FRA-Probe must be correlated to the voltage/current range of the EXD via factors. In this way, the Zahner potentiostats can control the EXD. In the illustration below, the correlation factor (G) - for the voltage signal - between FRA and EXD is 20. If a voltage of +100 V is to be applied via the EXD, a voltage of +5 V is applied to the FRA interface.
Installation
The FRA-X is connected to a IM7 potentiostat via I- and E-probe connection cables. The cables on one side are connected to I- and E-probe Lemosa connections at the front panel of IM7 potentiostat and on the other side to the back panel of the FRA-X. Moreover, the FRA-X needs to be powered using a mains cable.
The voltage and current measurements in many modern external sources or loads (EXDs) are often comparably slow, or not phase-coherent (especially in the case of digital signal processing paths, and especially for more elevated frequencies). This behaviour is not compatible with measuring EIS, while the EXDs may at the same time be able to follow an external signal with its current or voltage output with comparably fast dynamics (low rise times). Therefore, the FRA-X can be considered an upgrade to the EXD to access the EIS technique by enabling fast, dynamic and reliable voltage and current measurements. This is performed by external voltage- and current transducers, directly by the FRA-X (i.e., the Zahner device), separate from the EXD electronics (galvanically isolated).
Note
Different EXDs have different types of analog input ports, hence the user is obliged to custom-build an adapter cable to connect FRA-X to the EXD. However, Zahner a suitable adapter cable for Regatron© power supplies is included.
On the front panel of the FRA-X, three connectors are available for the current transducer, voltage transducer, and excitation signal output, respectively. The “excitation signal out” port will be connected to the analog control input port of the EXD. The current and the voltage transducers are connected to the FRA-X via the defined current- and voltage transducer ports. The PAD42 card in the FRA-X setup shown below is optional.
Note
The current-transporting cables from the EXD to the DUT should be twisted around each other to mitigate the induction effect.
Caution
The FRA-X is delivered with a voltage transducer from TESTEC which is powered up by USB connection, which must be used with a separate USB power supply. Powering the USB cables directly from a computer can lead to artefacts in the measurement.
Offset Adjustment
The offsets can be adjusted in the Zahner Lab software or via Python / C++.
Current Transducer Dimensions
For measurement of current in the DUT, the current carrying cable must be routed to go through the current transducer.
Note
If multiple cables are run between the EXD and the DUT or if the cable is too thick to fit into the current transducer ring, the user must custom-build a solution (i.e., a copper assembly) so that the current transducer can properly measure the current.
The dimensions of the SIGNALTEC current transducers are provided below.
Current Transducer |
Diameter (mm) |
Maximum Current |
|---|---|---|
CT100 |
28.2 |
±100 A |
CT500 |
38.2 |
±500 A |
CT1000 |
38.2 |
±1000 A |
CT2000 |
70.0 |
±2000 A |
CT6100 |
140.3 |
±6100 A |
CT100
CT500 / CT1000
CT2000
CT6100
Specifications
Current Ranges |
±100, ±500, ±1000, ±2000, ±6100 A (select on order) |
Voltage Ranges |
±5, ±70, ±140, ±700, ±1400 V (select on order) |
Analog Control Output |
±10 V (DC + AC) ±5 V AC |
EIS Frequency Range |
10 µHz … 100 kHz (defined at FRA-X) |
Note
The EXDs with higher specifications (high current/voltage range) will usually have longer rise times. Hence the user should not use an unnecessarily big EXD with the IM7/c/x potentiostat and FRA-Probe for the EIS measurements. Otherwise the usable bandwidth will be limited.