Cell Voltage Monitoring Solution for Electrolyzer

Caustic soda and hydrochloric acid, produced in electrolyzer plants, are fundamental materials used in varieties of industries; chemicals, pharmaceuticals, petrol-chemicals, pulp & papers, etc. Proper control of the process brings you stabilized quality of products with the vast operational profit. Ion-Membrane electrolysis bath is the most effective among all types of electrolyzer in caustic soda production. A Membrane has life time. It should be maintained periodically. To prolong operating life, the electrolyzer plant should be monitored for optimized control.

Electrolytic Plant

Electrolysis Application

Caustic soda (NaOH) and Chlorine (Cl2) are generated by the electrolysis of Salt (NaCl). Electrolyzer is used to produce these fundamental materials.  The latest technology of this electrolysis system called “Electrolyzer” is used ion exchange membranes, and Ion exchange Membranes in electrolyzer is called "cell". An electrolysis bath is consisted of many cells. Cells are connected by series connection to each other. A Cell has life time, so it should be maintained periodically by monitoring the Cell Voltage.
There is a lot of cells in electrolyzer, so multi-channels data acquisition system is required to monitor the cell voltage. And Input channels of measurement instrument is appeared a few hundred voltage, so  the internal circuit of measurement instrument has to be isolated from external circuits for cell voltage monitoring, and data acquisition system with high withstand voltage is required.

Electrolysis Application


Electrolysis Application requirement

Multi-channel data logging

A Membrane used Ion-Membrane electrolysis bath has life time. The owner of electrolytic plant has to know each cell condition. The owner monitors each cell voltage to look at the cell condition. Each cell voltage is a few voltage (e.g. 3Vdc), but an electrolysis bath has a lot of cells (e.g. 100 cells or more), the maximum voltage may be a few hundred voltage (e.g. 300Vdc or more). Cell voltage monitoring for electrolysis bath is required multi-channel data logging system.

High withstand voltage to common mode signal with high voltage

Each cell voltage is small, but a few hundred DC voltage is appeared to both terminals (positive and negative terminal for each channel) of the last channels. It seems like a common mode signal that it’s appeared a few hundred voltage to both terminals. In this case, The internal circuit of measurement instrument has to be isolated by High withstand voltage to external circuit.


Solution for Cell Voltage Monitoring of Electrolysis Bath

Multi-channel data logging solution

GM10 can support the measurement of up to 420 analog input channels by using the GX90EX expansion module. Also the GM10-2 large capacity memory model can support the recording of up to 1,000 channels including MATH channels and Communication channels.

Modular style GM10 data acquisition system

Chain up to 6 subunits

High withstand voltage module

A few hundred DC voltage is appeared to both positive and negative terminal of a channel, so between internal circuit and external circuit of a measurement instrument has to be insolated. GX90XA-10-V1 analog input module with High withstand voltage can isolate between both circuits by 600Vrms/Vdc withstand voltage.

gx90xa/block diagram

Analog input module with High withstand voltage

  • Number of input: 10 channels per module
  • Input type: DC Voltage / Thermocouple / Digital Input
  • Common mode voltage for measuring input:
    600V ACrms / 600V DC




  • Chemical

    Chemical plants rely on continuous and batch production processes, each posing different requirements for a control system. A continuous process calls for a robust and stable control system that will not fail and cause the shutdown of a production line, whereas the emphasis with a batch process is on having a control system that allows great flexibility in making adjustments to formulas, procedures, and the like. Both kinds of systems need to be managed in available quality history of product, and to be able to execute non-routine operations. With its extensive product portfolio, experienced systems engineers, and global sales and service network, Yokogawa has a solution for every plant process.

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