Fornos elétricos

GPC power controller for autoclave treatment of laminated safety glass

Learn how to control resistive heaters, applied to an autoclave curing process, for the production of laminate safety glass

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TK
Saída Volt ou mA de uso geral
650L
Indicador/Limite do alarme de segurança (FM)
GPC
Single/Two/Three phase Advanced Power Controller up to 600A

Efficiency in temperature control of heating elements in laminated glass polymerization processes in autoclave

The GPC power controller ensures perfect cohesion between PVB foil and glass sheets in autoclave curing processes of the material in the laminated glass production process.
With the power controller in three-phase mode, it is possible to control three-phase heating batteries with:

  • perventional maintenance;
  • integration of the control system with PLC system;
  • use of safety devices (limit switch) with alarm threshold when the temperature is reached.

Overview

  • Application: Control of resistive heaters applied to an autoclave polymerization process for the production of laminate safety glass
  • Products: Power controller GPC3PH 250A / Limit controller 650L / Pressure sensor TK for overpressure limit

The Process

Laminated glass products are widely used in the automotive (windshield), construction and shipbuilding sectors where high safety standards are required in case of breakage or impact.

The protection is guaranteed by the application of a sheet of PVB (plastic material) between two glass sheets.

The production process consists of:

Phase 1: Coupling the PVB sheet with the glass sheets.

Phase 2: The glass plates are placed in bags in which a vacuum is created. This process is necessary to eliminate any air bubbles between the glass and the PVB sheet and ensure perfect adhesion and positioning of the various layers.

Phase 3: Polymerization (heat treatment under pressure in autoclave) process of the product – producing a single solid glass plate.

Figure 1 – Plant scheme

The challenge

The application concerns the polymerization of the material in the autoclave, a particularly delicate phase in the laminated glass production process, which must ensure perfect cohesion between the PVB sheet and glass sheets. This is required to get the characteristics of resistance to breakage and perfect visibility.

The autoclave with a diameter of 4mt (13ft) and a length of 15mt (49 ft) is used to produce armored multilayer glass (both flat and curved) for the automotive, military and naval sectors.

The autoclave treatment consists of a thermal cycle (max 150 °C / 302 °F) under pressure (max 12bar) divided into 5 phases.

  • Pressurization
  • Heating
  • Temperature maintenance
  • Cooling
  • Depressurization

Resistors packs for a total of 500KW connected in a three-phase configuration are applied for the heating process.

To ensure the efficiency and stability of the heating, the diagnostic of the product and of the heaters are quite important.

Product benefits

GPC 3 Phase Power Controller

  • Range: from 40A to 600A
  • Simple and flexible configuration with the GF_eXpress configurator tool.
  • Portable display for local data access and simple configuration by selecting the previous recipe.
  • Command mode: configurable
  • Heater breakage alarm with self-learning
  • Connectivity: all the most commonly used Ethernet field buses
  • Complies with SCCR UL 508 100KA

TK Pressure Sensor

  • Robust and resistant electronics, IP 65/67 protection
  • Range -1 / 5bar (15bar overpressure protection)
  • Output signal: 0-10V

650L overtemperature safety threshold

  • System safety overtemperature alarm relay
  • Factory Mutual Certificate (FM)

Solution

Advanced Power Control
GPC Power controller to drive 3 phase heater system

Preventive maintenance
The sparks on power terminals due to improper tightening could be a cause for potential fire which can be avoided by the continuous monitoring of the temperature, provided by the 12 thermistors integrated in the terminals (Figure 3) combined with a specific on HOLD automatic procedure.

Figure 2 – Partial heater break alarm

Partial or total heater break of one leg can be the cause of reduced transfer of energy to the process. A specific diagnostic (Figure 2) and a compensation algorithm between the phases
available with the GPC Power Controller enables the power controller to transfer the required energy despite the failure.

Figure 3 – Terminals temperature continuous monitoring

 

Control system integration
The firing of the power controllers can be performed through a PLC system. The Ethernet communication protocols (ProfiNET, Ethercat, Ethernet / IP, Modbus TCP / RTU) on the GPC Power Controllers enables it to be integrated with plant network and becoming part of the central control system for a seamless operation.

650L – Over temperature limit switch
In the case of autoclaves or heat treatment ovens, the use of safety devices (LIMIT SWITCH) is required to control the heating process.
The function is to open the control circuit (Figure 4) when a defined safety temperature value inside the autoclave is exceeded.
650L alarm thresholds meet the required safety requirements also providing diagnostic information (number of alarm interventions, total alarm intervention time) useful for evaluating any corrective actions on the system.

  • Operator interface with large LCD display
  • Scrolling diagnostic messages
  • Retentive alarm condition
  • Dedicated front key for alarm reset
  • Modbus RTU communication
  • Configuration access with 3 password levels
  • FM (Factory Mutual) certification
Figure 4 – Control Scheme