Control systems in concrete batching plants

“Stetter concrete batching plants are used to produce both precast as well as ready mix concrete. Some of our customers use mixers with dual discharge options with one outlet delivered to a precast yard and the other to Stetter concrete transit / truck mixer.”

Different types of control systems used in concrete batching plants

Stetter concrete batching plants uses different types of Stetter control systems in different types of projects in the table mentioned below. The control system selection is purely based on the type and the capacity of the plant that the customer is looking to opt for and it is obviously based on the projected concrete requirement for the project or based on the demand in the particular location in case of RMC for example.

What role does sensor technologies play in effective functioning of concrete batching plants?

As such there is no technology driven sensors being used in Stetter concrete batching plants. But the technology can be derived or brought in with the help of sensors. It matters where these sensors are being installed or applied in the control system. In Stetter concrete batching plant, the sensors are all interconnected through a Programmable logic controller (PLC) system where the data is received through the sensors which are validated and corresponding actions are taken.

So in this case, the PLC does the job and not the sensors directly. The sensors give a feedback of an event or mechanism that converts an analog signal into a digital signal so that the same can be validated in the PLC. There are various sensors used in Stetter concrete batching plant. The challenging part is how these sensors are adopted and utilised in varied applications. In our system, we are using the following sensors of moisture probe for measuring sand moisture level, temperature sensor for measuring the concrete temperature and water temperature, pressure sensor for measuring the pressure in the pneumatic lines, proximity sensor, limit switches, reed switches, zero speed sensors, pull cord and belt sway switches, etc.

Could you throw some light on the R & D and testing procedures that are conducted while finalising the hardware components for the control systems?

Hardware selection plays a major role. We have to check the suitability for the requirement and have it certified by agency for conformity and standards. Availability of the hardware in the market continuously helps and after selection, the hardware will be tested in lab for functional requirements. Then the hardware will be put under field validation for a defined period or for a defined production quantity and after successful trials, the hardware will be released for regular production.

Do you offer customised control systems to cater to varied requirements of concrete batching plants?

Depending on the projects and the type of concrete produced, there are special requirements. For example: precast, hydropower projects, dam, nuclear power projects have various types of concrete requirement. Some are temperature controlled with special additives, sometime the size of the aggregate itself is too big. This sometimes require additional mixing time or premixing time, so we have the option to customize the control system to address such requirement.

Schwing Stetter India offers concrete batching plants to cater to varied requirements of the customers. Stetter control systems functional features are ethernet based communication between PC and PLC, MPI-TSA (USB communication), human machine interface (HMI) colour display option to enter batching plant parameters, supervisory control and data acquisition (SCADA) software, panel mounted keypad, control desk, maintenance scheduling, analog channels configurable, skip up delay timer, authority based stock adjusting, individual tolerance for all ingredients, target printing including moisture correction, variable frequency drive (VFD) for cement batching (for accuracy on bigger screw conveyor), slack steel time setting, on / off delay for vibrators, cement silo change over from any silo to another silo, production scheduling, timer based scheduling, maximum aggregates, cement, admixture and weigher supported, number of batches in single production, moisture correction allowed for aggregate bin as manual input, auto moisture correction for aggregate bins, possibility to connect any number of vibrator, option to connect 5/3 way valve for number of aggregate, batch hold option to stop production in between, cement silo level indication and weigher calibration in SCADA and HMI, manual consumption registration, stock reconciliation and input output status in SCADA.

Do you find the automated control systems useful to execute various tasks? What are the advantages?

Yes, the automated control systems are critical for the batching plant operation to execute various tasks. The present control system can produce concrete manually as well as in a fully automatic mode. So practically one can visualize the time and accuracy level of a manually batched concrete with respect to the one produced with auto batching.

• Better accuracy with repeatability.
• Better output.
• Elimination of human error.
• Fully automated, no need of manual intervention.
• Assured quality.
• Complete traceability of the materials batched with percentage deviation.
• Measurable and accountable through resource planner integration.

Do the control systems have adequate provisions to handle multi-mixer plants (ready-mix and for prefabrication plants)?

Stetter concrete batching plants are used to produce both precast as well as ready mix concrete. Some of our customers use mixers with dual discharge options with one outlet delivered to a precast yard and the other to Stetter concrete transit / truck mixer. Here achieving output becomes a question due to the process that is involved in precast concreting. Recently, there are new requirements that have come up to handle this scenario in a different manner to increase the output and to optimise the space requirement for the equipment installation which has obviously taken us in path of customized new product development (NPD).

Tell us about the features incorporated in the control system to avoid sudden and unexpected component failure.

In Stetter control systems, we have maintenance module where we can configure all regular maintenance related activities. So the system will alert in advance for maintenance in case if it is due. Apart from that we have an enhanced system, an online dashboard where the customers can fully configure the tool for their entire facility which will give a clear idea right from the component life cycle monitoring to periodic maintenance scheduling. We are offering this solution in the form of a software as a service (SaaS) model.

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