PLC and SCADA Control Panels for Refrigeration

Control cabinet is the coordination centre for every piece of equipment in an industrial refrigeration system. When the control cabinet follows the right logic, the refrigeration compressors start in the correct order, the defrost cycle runs automatically, and the cold store temperature holds to ±0.5°C. When the control cabinet fails, the whole line stops. Tan Long designs and builds control cabinets with integrated PLC, HMI and SCADA — tested to IEC 60439 and TCVN 6592, optimised for Vietnamese industrial refrigeration operating conditions.

What is a control cabinet?

Control cabinet (also called a control board, electrical panel or control cabinet) is the integrated operating centre for all electrical and electronic equipment. Its job is to coordinate, protect and closely monitor the equipment in refrigeration system. Everything from switching the refrigeration compressors in sequence, controlling the defrost cycle and regulating fan speed industrial refrigeration through to logging faults is handled centrally inside the cabinet enclosure.

Basic construction of a control cabinet

A system control cabinet A standard industrial cabinet for the refrigeration industry comprises three main functional blocks: the power block (MCCB, MCB, contactors, inverters), the logic control block (PLC, protection relays, I/O modules) and the human-machine interface block (touch HMI screen, indicator lights, push buttons). The enclosure is made from galvanised sheet steel at least 1.5 mm thick with a powder-coated anti-corrosion finish, rated from IP54 to IP65 depending on the actual installation environment.

Operating principle in a refrigeration system

In the operating diagram, the PLC is the brain of the control cabinet. It continuously receives digital signals from discharge and suction pressure sensors, PT100 temperature sensors placed at the cold storage and current sensors on each compressor. When a parameter exceeds its safe setpoint, the PLC immediately commands the contactor or the inverter to take protective action within an extremely short time, usually under 100 ms. This is the response speed advantage that traditional relay systems struggle to match.

Applications of the control cabinet by industry

System control cabinet designed and installed by Tan Long are now running effectively at seafood processing plants, food cold stores, key industrial parks and medical facilities nationwide.

Seafood processing and frozen food: In this segment, the control cabinet is connected directly to run the mesh belt IQF freezer, wind tunnel and the contact plate freezer lines. The PLC synchronises belt speed, freezing chamber temperature and freezing time precisely. This keeps the IQF individual quick freezing process to standard, with the required product core temperature of -18°C reached in under 30 minutes.
Commercial cold storage and logistics: For transport and storage operators, the SCADA solution integrated into the control cabinet allows 10 to 50 cold rooms to be managed simultaneously from a single central screen. The system records temperature data continuously and exports periodic PDF reports, making it easy for the business to meet demanding international temperature traceability standards such as HACCP, BRC and FDA.
Beverage production and industrial cooling: At water processing plants or facilities using water chiller, control cabinet the cabinet manages several chiller sets working in parallel. The system can adjust the load automatically based on the actual outlet water temperature, keeping the refrigerant stable and minimising wasted electricity.

With long experience in mechanical and refrigeration engineering, Tan Long commits to delivering specialist control cabinet solutions that match the specific operation of each industry precisely, contributing to better business performance for our partners.

Classifying control cabinets by technology

In industrial refrigeration today, choosing the right control cabinet depends on the scale and technical requirements of each project. There are three common technology lines: hard-wired relay systems, PLC programmed solutions and SCADA monitoring systems.

Comparison of the common control cabinet lines:

Criteria	Relay/contactor system	PLC + HMI cabinet	PLC + SCADA system
Practical applications	Single machines or systems with fewer than 5 units	Cold stores from 200 to 5,000 m³	Large plants, multiple stores, remote monitoring
Automation capability	Limited to basic levels	Complete and flexible	Comprehensive and intelligent
Remote monitoring	Not supported	Via the HMI at the installation point	Via the local LAN or the internet
Data storage	No storage function	Limited by HMI memory	Unlimited storage on a server
Sequential start	Hard to do accurately	Optimal for refrigeration compressor	Optimises the whole system
Best suited to	Simple evaporators, condenser fans	IQF belt freezers, multi-temperature cold stores	Seafood plants, cold stores above 3,000 tonnes

Select control cabinet using relays is usually for simple systems with a low investment budget. Meanwhile, the PLC control cabinet with an integrated HMI screen is the gold standard for most industrial cold storage installation projects in Vietnam, because it balances cost against performance.

For large food groups in particular, investing in a control cabinet combined with a SCADA system is the necessary solution for managing several cold stores centrally from a single point, allowing parameters to be monitored and adjusted instantly from a smartphone or an office computer.

Tan Long control cabinet specifications and standards

Tan Long designs and builds control cabinet directly at our own workshop in Tay Ninh (formerly Long An), ensuring strict quality control at every stage to international IEC standards. Every system is customised to the actual technical requirements of the project rather than following fixed models, to deliver the best operating performance for the customer cold storage of the customer.

Category	Parameter / standard
Cabinet shell	Galvanised steel ≥ 1.5 mm thick, powder-coated against corrosion
Protection rating	IP54 (ordinary machine rooms) – IP65 (wet or chemical environments)
Input voltage	3 pha 380V – 440V AC, 50 Hz
Control capacity	0,75 kW – 375 kW+ (1 HP – 500 HP+)
PLC controller	Mitsubishi iQ-R/F, Siemens S7-1200/1500, Schneider M221/M241, Omron CP2E (to customer requirement)
HMI screen	7″–15″ colour touch screen, Vietnamese interface
Inverter (VFD)	Integrated for compressors, fans evaporative condenserand cooling pumps
Communication protocol	Modbus RTU/TCP, Profibus, Ethernet/IP, OPC-UA, RS485
Design standard	IEC 60439, TCVN 6592
Control supply	24V DC (independent, safe control circuit)
Compatible refrigerants	NH₃ (Amoniac), R22, R404A, R134a, R507, CO₂ (R744)

The choice of protection rating for the control cabinet is extremely important for equipment life. IP54 keeps out dust and splashing water from all directions, which suits standard machine rooms. IP65 keeps out dust and pressurised water jets completely, which is particularly necessary in environments where floors are washed regularly or in high-humidity areas near industrial evaporators. For seafood processing areas that are cleaned frequently with high-pressure hoses, Tan Long recommends IP66 so the equipment can withstand strong water jets without damage to the electrics inside.

The control cabinet manufacturing and installation process at Tan Long

Tan Long applies a standardised 6-step process from survey to final acceptance, so that every control cabinet operates stably in harsh industrial environments.

Step 1. Technical site survey: Tan Long engineers visit the site to determine how many units have to be run and the total system capacity. A thorough assessment of the installation environment — temperature, humidity and chemical exposure — is the basis for deciding the IP rating and the type of components inside the control cabinet.
Step 2. Schematic design: Engineers separate the power circuit and the control circuit methodically. All calculations for cable cross-section and protection devices such as MCCB, MCB and ELCB follow IEC 60364, ensuring accurate protection coordination between levels.
Step 3. PLC programming and HMI interface design: Based on the agreed operating logic, engineers program the PLC control cabinet. Key algorithms such as sequential compressor starting, automatic defrost and multi-level pressure protection are built in. The HMI interface is designed in clear Vietnamese so operators can follow system status easily.
Step 4. Fabrication and assembly at the workshop: The enclosure is fabricated precisely at the Tan Long workshop in Tay Ninh to CAD drawings. Equipment is assembled to the layout drawing to ensure optimal heat dissipation clearances. All signal wiring in the control cabinet is clearly numbered, which makes later maintenance far easier.
Step 5. FAT (Factory Acceptance Test): Before despatch, every control cabinet goes through strict insulation testing to IEC 60439. Tan Long simulates assumed fault situations to verify how the system responds. The FAT results are recorded in a detailed handover report for the customer.
Step 6. SAT installation, acceptance and training: Engineers carry out installation and live testing on site (Site Acceptance Test). Once the control cabinet has kept the cold store system running stably for 72 hours continuously, Tan Long hands over the as-built diagrams and runs in-depth training for the customer technical team.

Following this strict process not only confirms Tan Long reputation in cold storage design but also gives the investor confidence in the durability and safety of the control cabinet.

Indicative control cabinet price list 2026

The actual unit price of a control cabinet varies with the control technology, the total connected load, the number of I/O signal points and any demanding communication protocol requirements. At Tan Long we use genuine components from specialist brands such as Mitsubishi, Siemens and Schneider to ensure the highest system stability.

Below is the indicative price range for the common control cabinet lines at Tan Long:

Control cabinet type	Capacity range	Indicative price (VND)
Simple relay/contactor system	5 to 50 kW (7 to 67 HP)	Contact
Standard PLC control cabinet with HMI	15 to 150 kW (20 to 200 HP)	Contact
PLC cabinet for multi-temperature cold stores	50 to 375 kW (67 to 500 HP)	Contact
SCADA control cabinet with IoT integration	Designed to the scale of the project	Contact

The prices above are indicative at the current time and exclude on-site installation labour, power cabling and peripheral measuring devices. For the best technical solution and an accurate price for each type of refrigeration compressor or specific production line, please contact the Tan Long engineering team directly for a site survey and in-depth advice.

Tan Long does not only supply products but delivers a control cabinet solution that optimises operating performance and saves energy cost for the business over the long term.

Why choose Tan Long to supply your control cabinet?

Tan Long is a refrigeration engineering joint stock company with more than 20 years in industrial refrigeration, serving seafood and food processing plants and large-scale cold stores across Vietnam.

In-house manufacturing: its own factory in Duc Hoa 1 Industrial Park, Tay Ninh (formerly Long An), with no dependence on outside subcontractors.
Turnkey D&B capability: design and construction under one roof, reducing the risk of a gap between the drawings and what is actually installed.
Complete documentation: equipment is handed over with technical files and CO/CQ certificates of origin.
Engineers with field experience: advice based on each plant's actual system configuration rather than selling from a catalogue.
Support after handover: the technical team is on hand for operation and maintenance throughout the equipment's life.

For advice on a specific configuration, please contact Tan Long's engineering team or see the projects already delivered.

Control functions specific to industrial refrigeration systems

Control cabinet for an industrial refrigeration system has to handle specific tasks that ordinary industrial cabinets do not support. In practice, a temperature deviation of just 2°C or a 10% rise in discharge pressure can ruin an entire high-value consignment in store. At Tan Long we optimise the following functions to ensure safety:

Sequential compressor start: The PLC controls the starting order of each refrigeration compressor based on the actual heat load, with a delay of 30 to 120 seconds between each start. This removes simultaneous inrush current, protects the internal electrical network and extends motor life by 20% to 30%.
Automatic defrost control: The defrost cycle for the industrial evaporator can be set flexibly by time or by a sensor that detects accumulated frost. Control cabinet coordinates the whole sequence — stopping the compressor, opening the hot gas valve and switching on the drying fan — without interrupting the cooling mode of the other chambers in the system.
Pressure control and multi-level protection: High and low pressure sensors are wired directly back to the central PLC. When discharge pressure exceeds the setpoint (usually 18 to 22 bar with R404A, or 15 to 17 bar with NH₃), the system raises a level 1 alarm. If the pressure keeps rising within 30 seconds, the control cabinet shuts the compressor down automatically and writes a detailed fault log.
Inverter control for energy saving: Condenser fan and cooling pump speeds are adjusted automatically to the actual load, saving the business 20% to 40% of electricity compared with fixed-speed operation. On a cold storage design project of 1,000 m³, that saving is equivalent to roughly 150 to 250 kWh a day.

Investing in a system control cabinet built to technical standards not only protects the equipment but is also the key to optimising operating cost for the business over the long term.

Representative control cabinet projects delivered

Tan Long is a trusted partner that has designed and installed control cabinet systems directly for dozens of food plants and large cold stores nationwide. You can assess Tan Long real delivery capability through the key projects below:

Kyokuyo Vina Foods: This is a modern NH₃ refrigeration system project comprising 08 high-speed IQF belt freezers, contact plate freezers and a flake ice machine system built by Tan Long. The entire operation is coordinated centrally by a SCADA control cabinet system made by Tan Long, supporting remote monitoring of parameters over the local network.
Lotte F&G Vietnam (Tay Ninh): Tan Long installed a PLC control cabinet system to run a multi-temperature cold store complex. The system integrates inverters for the whole refrigeration compressor set and the condenser fans, cutting electricity consumption by up to 25% compared with the previous control technology.
C.P. Vietnam (Cu Chi, Ho Chi Minh City): The project uses a control cabinet with in-depth SCADA integration to monitor and coordinate the refrigeration system at a livestock processing industrial complex. This solution ensures cooling performance and also supports automatic temperature data traceability, meeting the demanding verification requirements of global HACCP standards.

To see other projects or to get advice on the optimal control cabinet solution for your business, please visit the project portfolio page or contact the Tan Long engineering team directly for the fastest support.

Operating and maintenance notes for the control cabinet

Operation control cabinet to the correct technical process not only extends component life but also prevents unplanned shutdowns entirely, keeping the whole refrigeration system stable.

Isolate the supply before opening the cabinet: This is an absolute safety rule. Technicians must switch off the main breaker and check carefully with a voltage tester before reaching any part inside. Systems running refrigeration compressors of 15 kW (20 HP) and above usually use 380V, which carries a very high risk of electrical accident if the protective procedure is not followed.

Recommended periodic maintenance schedule for the control cabinet:

Interval	Detailed work items
Monthly	Check the operating temperature and clean the cabinet cooling fan filter
Every 3 months	Check and tighten cable lugs, check the balance of the 3-phase supply voltage
Every 6 months	Measure power circuit insulation resistance, check the condition of contactor and protection relay contacts
Annually	Recalibrate the temperature and pressure sensors and update the software for the PLC

Only engineers or technicians properly trained in industrial electrics, with a full grasp of the circuit diagram of the control cabinet, may carry out repairs or replace components inside the system.

Investing in a system control cabinet built to technical standards is not only a safety measure for the equipment but also the key to optimising operations and saving energy cost over the long term. With deep experience and thousands of successful projects, Tan Long is confident in delivering control cabinet products of the highest quality, durability and modernity for your industrial cold storage system.

Are you looking for professional control panel design and installation solutions for your project?

Contact our Hotline now: (+84) 933357058 (Mr. Thinh) to speak to a consulting engineer directly.
Request a quick quote:Here.

Tan Long is always ready to work alongside your business to build refrigeration systems that are safe, intelligent and effective.

Frequently asked questions about control cabinets

How does a control cabinet differ from a power distribution board?

A power board (MCC — Motor Control Center) only switches and protects the supply to each motor. A control cabinet adds the logic brain (PLC), an HMI screen and communication modules — allowing automatic coordination by algorithm with no manual intervention.

Do Tan Long cabinets come with an HMI screen?

Yes. All Tan Long PLC cabinets include a colour touch HMI screen, with the interface programmed in Vietnamese to the actual operating requirements of each project.

Can the cabinet connect to an existing SCADA system?

Yes. Tan Long supports connection over standard industrial protocols: Modbus TCP/IP, Modbus RTU, Profibus and OPC-UA — compatible with most SCADA software on the market such as Wonderware, Ignition, WinCC and InTouch.

Do Tan Long cabinets come with a warranty? How are faults handled?

Tan Long warrants cabinets under contract, with technical support remotely and on site. An engineer is on site within 24 hours in Ho Chi Minh City and neighbouring provinces.

Can the control cabinet be monitored remotely by phone?

Yes, with the SCADA + IoT cabinet line. Operating engineers follow store temperature, system pressure and the status of each compressor through an app on a phone or a computer, wherever they are.

Is the cabinet suitable for NH₃ (ammonia) refrigerant?

Yes. Tan Long cabinets are designed to be compatible with systems using NH₃, R404A, R134a, R507 and CO₂. The pressure sensors and control valves are selected according to the chemical characteristics of each refrigerant.

What is the difference between a PLC control cabinet and SCADA?

A PLC is a programmable logic controller — it processes signals and issues control commands in real time, locally. SCADA (Supervisory Control And Data Acquisition) is the higher monitoring layer — it collects data from several PLCs, stores history, displays trend graphs and allows remote control. A large system usually uses both: the PLC handles local control while SCADA monitors and reports across the whole plant.

Request advice and a quotation

Tan Long designs and builds industrial refrigeration equipment at its plant in Duc Hoa 1 Industrial Park, Tay Ninh (formerly Long An), so capacity and dimensions can be adjusted to the actual site. Call 0933 357 058 (Mr. Thinh) or send a quotation request with your output per shift and your main product type.