What is potentiostat?
as a whole is negative feedback amplified output system, and the protected object (such as a buried pipeline) constitutes a closed-loop regulation, through the reference electrode to measure the potential of the energized point, as a sampling signal and control signal for comparison, to achieve control and adjust the polarization current output, so that the energized potential can be maintained at the set control potential.
The potentiostatic apparatus itself is a branch of a rectifier, with constant potential and constant current function. Constant potential means that the reference electrode feedback is used as a constant standard to control the output of the collator. If there is a problem with the constant potential, such as interference, damage to the reference electrode, etc., then the constant current function is needed to keep the current output constant, which means that the current output remains the same and the voltage changes.
Application of potentiostat
are instruments mainly used in electrode process kinetics, electroanalysis, electrolysis, electroplating, metal phase analysis, metal corrosion rate measurement, and various corrosion and corrosion protection studies as well as electrochemical protection parameter testing.
It is mainly used in electrode process kinetics, electroanalysis, electrolysis, electroplating, metal phase analysis, metal corrosion rate measurement, and various corrosion and corrosion protection studies as well as electrochemical protection parameter testing.
It also can be used independently or supplemented by a signal generator, DC oscilloscope, logarithmic converter, X-Y recorder, etc. for a variety of dynamic and static, transient and steady-state test measurements, suitable for factory enterprises, scientific research, teaching experiments, and new product development and a variety of measurement purposes.
Structural composition of potentiostat
The ideal biological potentiostat circuit is mainly composed of four parts: operational amplifier, electrode system, sample solution, and feedback resistor. The electrode system consists of a working electrode, reference electrode, and auxiliary electrode. The function of the working electrode is to make the electrochemical reaction of the solution be measured under the condition of applied potential, to determine the current generated on this electrode. The reference electrode is used as the reference electrode for the working electrode and the auxiliary electrode. The feedback resistor mainly converts the current generated by the working electrode into voltage to meet the requirements of the back-end acquisition input.
The core of the constant potential meter is the comparison amplifier, which is composed of a differential amplifier with deep negative feedback, generally using an integrated operational amplifier with good performance as its input is the control and reference circuit, the output to follow the amplification, control phase shift, oscillation, and other circuits to generate trigger pulses, the polarization power supply is composed of the thyristor rectifier circuit, and the output is adjusted by changing the conduction angle.
Potentiostat working principle
The working principle of the potentiostat apparatus is as follows:
The rectifier voltmeter in the potentiostat serves to adjust the given potential of the pipe. The measured potential of the pipe ground is compared with the reference potential and a potential difference can be found, which can be controlled by a magnetically saturated reactor on the output of the rectifier transformer via the line reactor output. The tube ground potential is compared with the reference potential to find a voltage difference, this voltage difference can control the rectifier transformer output, is through the magnetic saturation voltage device to control. If the tube ground potential is shifted in the positive direction of the reference electrode, an increase in the protection current occurs, and if it is shifted in the negative direction, a decrease in the cathodic protection current occurs. When several devices are connected in parallel, the time can be adjusted to prevent induction oscillations.
Types of potentiostat
Common classifications of potentiostats include thyristor potentiostat, high-frequency switching potentiostat, and cathodic protection console. Within each of these categories, there are many different specifications.
Explosion-proof potentiostat is an explosion-proof type forced current cathodic protection power supply with excellent characteristics such as high componentization and stable performance of thyristor constant potential meter. It can be added to the power supply of the current cathodic protection system. Explosive environments such as tank areas.
Remote control, remote transmission potentiostat
Remote control, remote transmission potentiostat is widely used to apply current cathodic protection to metal structures or equipment such as pipelines, cables, steel terminals, gates, ships, storage dumps, tanks, and coolers in soil, seawater, fresh water, and chemical media. The remote control and remote transmission cathodic protection system are equipped with remote control and remote transmission interface, which can realize data remote transmission and remote control (the instrument is equipped with Rs485). The system contains two completely independent constant potential meters and a switching circuit to control the work of two constant potential meters, which can realize the automatic conversion of fault into a constant current working state.
can be applied to the applied current cathodic protection of metal structures or equipment in soil, seawater, freshwater, chemical media, mainly used in regional applied current cathodic protection such as stations, with advanced technical performance indicators, high reliability and long service life.
Multichannel potentiostat is a multi-way independent current output device, each output current can be adjusted independently, not affecting each other. Each channel can realize constant potential control, constant current control, each channel also has manual adjustment, power on/off test operation mode, the instrument has over-current protection, lightning protection, anti-AC interference function.
Potentiostat specifications and features
|Potential control range||±2V, ±4
|Current control range||±2μA～±200mA total six grades can be continuously adjusted
|Slot voltage output range||±20V
|Reference electrode input impedance||not less than 109Ω
|Constant potential characteristic||±0.1% (F.S)
|Conversion rate||greater than 0.1V/μS
|External dimensions|| 320×240×90mm
1. Small potentiostat adopts low drift, high precision circuit system, original imported high power IC.
2. Equipped with power protection and automatic alarm function, stable and reliable work.
3. Touch keyboard, large screen LED double digital display, can simultaneously display constant potential and constant current.
How to use potentiostat?
When we want to use the biological potentiostat
for testing, we can usually operate it as follows. However, due to the different brands, there may be some differences, so we recommend that you also read the instruction manual in detail to operate.
(1) Turn on the potentiostat
a. Turn the biological potentiostat "manual setting" knob and "auto setting" knob counterclockwise to the end, turn the "manual/auto" switch to "auto "position, and the "measurement selection" switch to the "given" position.
b. Turn on the main power supply, and turn the power switch of the equipment to the "on" position, then the constant potential meter is connected to the power supply.
c. Turn the "Stop/Run" knob to "Run", then the power of the potentiostat is on.
d. Slowly adjust the "Auto Adjust" knob of the potentiostat, observe the potentiometer indication and stop adjusting when the set value is reached.
e. Turn the "measurement selection" switch of the constant potential meter to "C1" position, at this time the millivolt meter indicates the pipeline protection potential. If the equipment jumps to "fault", press the "reset" button switch to restore the operation status.
f. After completing the above operation, observe at least 0.5 hours, after the equipment has no abnormal heat and no alarm, record the output current from the ammeter, the output voltage from the voltmeter and the protection potential from the potentiometer.
(2) Turn off potentiostat
Turn the power switch of potentiostat apparatus to the "off" position, and adjust the knob automatically counterclockwise to the end.
(3) Manual operation
The potentiostat can be operated manually in case of equipment failure as confirmed by the electrical engineer.
The place where the potentiostat is installed should be suitable for ventilation and heat dissipation, and the equipment should be carried and placed lightly.
The installation must be wired according to the wiring diagram to ensure the correct polarity of the output power. And in the wiring place are clearly marked symbols "+" "-", first use a multimeter to test the terminals are accurate, and then try to power on the connector of the cable will then be sealed and installed, after the installation of equipment is complete The housing should ensure continuous good grounding performance.
Before energizing the installed constant potential meter for use, the natural potential of the pipeline must be measured, and the potential value should be around -0.6V. The point to note here is that if the pipeline comes with temporary use of cathodic protection equipment, the potential meter tested here is likely to be at -1.10V or lower. Next, the potential of the anode ground bed should be measured, and the coke back packing wrapped anode here the potential value will generally be between +0.20V to +0.30V CSE, note: if the packing uses galvanized iron sheet cylinders.
Precautions for using potentiostat
The following matters should be noted in the use of potentiostats.
1. All units of the potentiostat should always be kept clean and dry, and prevent the intrusion of dust and corrosive gases.
2. The insulation resistance of the glass electrode jack should not be less than 1×10^12Ω, and the dust cap must be screwed on after use to prevent the intrusion of external moisture and impurities.
3. When the instrument is not in use, the reading switch should be placed in the release position, and short-circuit the meter with a short-circuiting piece to ensure the safety of the meter when moving transmission.
4. Glycerol electrodes often pay attention to the full saturated solution.
5. Before titration, use the titrant to rinse the solenoid valve and rubber tube.
How to maintain potentiostat?
1. Observe the operation of potentiostat in the yin protection room every day, record the output current, output voltage, and given potential (given potential is determined as -1.50v in this project), and measure the potential of the constant potential meter.
2. When the biological potentiostat is running normally, measure the pipeline protection potential through the test pile regularly and keep records, if the value of pipeline protection potential is found to be more than -850mv, the professional should be notified.
3. Check the potentiostat for any abnormality at any time. If there is an equipment failure or abnormal phenomenon such as noise increase; output appears larger swing; box temperature exceeds 75℃ or smell the odor caused by equipment overheating, potentiostat should be turn off in time.
4. Potentiostatic apparatus should run continuously and uninterruptedly and can switch to manual operation when the automatic state of the equipment fails.
5. In case of potentiostat apparatus failure, it should be overhauled by electrical professional maintenance personnel.
How to order potentiostat?
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