Temperature control cabinet (temperature control panel) is the central device coordinating everything an industrial refrigeration system does — from reading sensor signals and processing control commands through to protecting equipment when a fault occurs. Without a control panel, a refrigeration system runs blind. This is the brain of the entire cold chain.
A temperature control panel in an industrial refrigeration system integrates a PLC or SCADA controller, inverters, protective relays and a display. It reads the signal from PT100 or Pt1000 temperature sensors, compares it with the preset setpoint, then controls the compressor, evaporators and defrost system according to a pre-programmed cycle. The common control range runs from −45°C (−49°F) to +10°C (50°F), covering freezer stores, chill rooms and blast freezers.
Tân Long designs and manufactures temperature control panels for industrial refrigeration systems from 5 kW to over 500 kW (6.7 HP – 670 HP), serving seafood processing plants, commercial cold stores and frozen food production lines nationwide.
What is a temperature control cabinet?
Temperature control cabinet is an integrated system combining electrical hardware with control software inside a dedicated enclosure. It acts as the brain of the whole system, receiving signals from the sensors, processing the logic and issuing operating commands to the actuators. In industrial refrigeration it also goes by other names: refrigeration control panel, control panel, or refrigeration system control panel.
Quite unlike a domestic thermostat, which does nothing more than switch on and off, an industrial temperature control cabinet manages far more complex tasks. It can coordinate several independent control loops at once, protecting the refrigeration compressor on high or low pressure parameters, monitoring electrical load and keeping a detailed operating log. Modern panels installed by Tân Long also raise fault alerts by SMS or email, so owners can keep an eye on things remotely.
In operating terms, the device works on closed-loop control. First the sensor measures the actual temperature inside the cold storage or the freezing equipment. The central controller then compares that reading with the setpoint, calculates the error and issues a correction to the compressor or the solenoid valves. The cycle repeats continuously at the controller's scan rate, PLC control cabinet which is extremely fast — typically 10 ms to 100 ms. Thanks to that instant response, temperature control cabinet keeps the storage environment stable, avoiding any temperature swing that would affect product quality.
Industrial temperature control panel construction
A system temperature control cabinet A standard industrial panel comprises 6 core components. Each one performs a specific technical function in maintaining a stable closed control loop for the refrigeration system.
1. Central processor (PLC/Controller)
This is the processing core that coordinates everything the panel does. The PLC control panel reads the input signals from the temperature and pressure sensors and the protection switches, then runs the configured program to issue commands at its outputs. The PLCs commonly used in the Vietnamese refrigeration industry today include the Siemens S7-1200, Mitsubishi FX5U and Schneider Modicon M221. For large systems above 200 kW, Tân Long usually recommends adding a supervisory layer of SCADA control cabinet for centralised management and optimised operation.
2. Temperature sensor
Temperature control cabinet receives and processes signals from dedicated probes such as the PT100 (a platinum resistance element with a range from -200°C to +850°C) or the Pt1000 for applications demanding the highest accuracy. A Class B PT100 has an error of only about ±0.3°C, holding the cold store temperature within a very narrow band. For small storage rooms, an NTC 10 kOhm sensor can be used to save cost, but it is less stable than a PT element across a wide temperature range.
3. Inverter (VFD)
This device controls the motor speed of the refrigeration compressor and the evaporator fans according to the actual load. Instead of traditional on/off operation, which wastes energy, the inverter slows the compressor once the target temperature is reached. In a temperature control cabinet Tân Long panel, this saves customers 20% to 40% of their monthly running costs.
4. Relays and contactors
These devices switch large electrical loads — compressors, fans and pumps — on command from the PLC. Thermal overload relays (such as the Schneider LR2D range) provide overload protection, opening the circuit automatically when current exceeds the set threshold so the motor is not burnt out. Depending on system capacity, Tân Long selects devices with the appropriate rated current, anywhere from 1A to over 630A.
5. Display and operator interface (HMI)
The HMI (Human-Machine Interface) lets technicians see actual temperature, equipment status and alarm history at a glance. Through the touchscreen (commonly 7 inch to 15 inch), the user can adjust the setpoint of the temperature control cabinet directly on site. On larger projects the system can connect to a PC for remote monitoring over the internet.
6. Enclosure and internal cooling
Bark temperature control cabinet is usually fabricated from 1.5 mm to 2 mm steel with a corrosion-resistant powder-coated finish, rated IP54 to IP65. In seafood processing environments with high humidity and cleaning chemicals, Tân Long always recommends an IP65 enclosure to keep water and dirt out. The internal cooling fan also matters a great deal: it holds the temperature inside the panel below 40°C, giving the electronics the longest possible service life.
Types of temperature control panel in refrigeration systems
Temperature control panels in industrial refrigeration fall into 3 main types, according to control technology and application scale.
| Panel type | Technology | Suitable scale | Remote monitoring capability |
|---|---|---|---|
| Simple relay panel | On/Off relay | Small cold stores < 50 m² (538 ft²) | No |
| PLC panel | PLC + HMI | Cold stores 50–5,000 m² (538–53,820 ft²) | Via Ethernet/Modbus |
| SCADA panel | PLC + SCADA server | Plants > 5,000 m² (53,820 ft²), multiple rooms | Via LAN/internet/4G |
Simple relay panel uses a mechanical thermostat or a single-loop controller such as the Autonics TC4 or Omron E5CN. It suits a small single-room cold store, with low capital cost (under 5 million dong for the control section), but keeps no log and raises no automatic alarms.
PLC panel integrates a programmable logic controller, managing several devices at once: the compressor, evaporator fans, solenoid valves and the defrost system. The PLC logs temperature history every 15 minutes, sounds a buzzer alarm when temperature exceeds the threshold, and restarts equipment in a safe sequence after a power cut. This is the panel type Tân Long builds most, accounting for more than 70% of our installations.
SCADA panel links several PLC panels back to one control centre, letting technicians monitor the entire plant from a single screen. A SCADA system logs operating data continuously, generates reports automatically and supports the traceability checks required by HACCP and BRC Food Safety. Tân Long has deployed SCADA control panel systems at seafood processing plants.
Temperature control principles in cold stores and blast freezers
Temperature control cabinet works to a strict control logic, divided into 3 main phases in each refrigeration cycle: pull-down, steady-state and defrost. Understanding this principle helps owners optimise running costs and protect their products.
1. Pull-down phase
This is the most demanding phase, when new product is brought into the cold store or blast freezer and the heat load spikes. At this point the temperature control cabinet commands the refrigeration compressor to run at full capacity to pull the temperature down quickly from ambient (typically 35°C to 40°C) to the setpoint. On large NH3 systems, the standard pull-down time for a 1,000 m³ freezer store is usually 8 to 12 hours.
2. Steady-state phase
Once the room has reached its setpoint, the temperature control cabinet switches automatically to maintenance mode. Here the PLC control panel modulates compressor capacity through the inverter or the unloader system (on screw compressors), holding the temperature steady while saving as much energy as possible.
3. Defrost phase
Over 6 to 12 hours of operation, frost tends to build up on the evaporator and reduce heat transfer. To deal with that, the temperature control cabinet triggers an automatic defrost cycle on the pre-programmed schedule.
- Small cold stores generally use electric defrost heaters.
- For large industrial systems, Tân Long favours hot gas defrost for the best results.
Typically, the maximum defrost time for a -18°C freezer store is set at 30 minutes per cycle. As soon as the sensor detects that the ice has melted, the temperature control cabinet ends the defrost automatically and returns to the cooling cycle, so the room temperature does not rise too far.
Tân Long temperature control panel specifications
To keep the system accurate and durable in harsh industrial conditions, every temperature control cabinet Tân Long designs meets the most demanding technical standards. The specification table below helps customers and technicians choose the right configuration for their cold storage installation project.
| Specifications | Detailed value |
| Supply voltage | 220V single-phase or 380V three-phase, 50 Hz |
| Control temperature range | -45°C to +10°C (suits both freezer and chill rooms) |
| Control accuracy | Very low error of ±0.5°C |
| Number of control loops (channels) | Supports 1 to 32 independent channels depending on system scale |
| Compatible sensors | PT100, Pt1000, NTC 10 kOhm, 4–20 mA current signal |
| Communication protocol | Modbus RTU/TCP, Profibus, Ethernet/IP (connects to the SCADA control panel) |
| Enclosure protection rating | IP54 (industrial standard) or IP65 (optional, for damp environments) |
| Ambient operating temperature | 0°C to +55°C |
| Certification | CE certified, IEC 60364 and TCVN 7447 |
The above parameters show that temperature control cabinet Tân Long panels not only meet accuracy requirements but also scale flexibly. The system integrates easily with a PLC control panel to run complex automated operating scenarios, optimising performance across the whole refrigeration compressor package and the evaporators.
Using components built to international standards keeps a temperature control cabinet in service for longer and minimises the risk of a failure interrupting the business's cold chain.
Temperature control panel applications by industry
A temperature control panel is not a one-size-fits-all device. Every industry has its own requirements for temperature range, communication protocol and food safety standards.
- Seafood processing and storage is the biggest application in Vietnam. Seafood freezer stores run at −18°C to −25°C (−0.4°F to −13°F), while IQF blast freezers must reach −35°C (−31°F) in under 30 minutes. A control panel in a seafood plant must include a continuous temperature data logger to satisfy the traceability requirements of the FDA (US) and EC No 853/2004 (EU).
- Fruit, vegetable and produce storage needs a narrower temperature band: 0°C to 10°C (32°F to 50°F) at 85%–95% humidity. The control panel must read temperature and humidity (RH) sensors simultaneously, then coordinate both the compressor and the humidification system within the same control loop.
- Pharmaceuticals and vaccines is the most demanding application of all. A temperature control panel for a pharmaceutical store must comply with GDP (Good Distribution Practice) and 21 CFR Part 11 (for export to the US), requiring an immutable audit log, user authentication and automated standard-compliant reporting.
- F&B food processing plants use control panels integrated with IQF lines and air-blast freezing tunnels. Temperature signals from the panel are shared with the plant SCADA system to optimise the production schedule and shift power consumption to off-peak hours.
How to choose the right temperature control panel
Choosing the right temperature control cabinet determines more than 30% of the operating efficiency and service life of the whole refrigeration system. To decide correctly, an owner should work from three core criteria: system capacity, the actual number of measurement points, and the communication protocol requirements.
- Selecting by system scale and capacity: For refrigeration systems under 50 kW serving a single cold room, a temperature control cabinet using relays and a single-loop controller is the most cost-effective choice. But for systems from 50 kW to 200 kW, or with two or more cold rooms, you must use a PLC control panel. This type manages the starting sequence and protects equipment such as the refrigeration compressor in the correct technical order. For systems above 200 kW, or those with demanding food certification requirements, integrating a SCADA control panel is essential for centralised monitoring and data storage.
- Determining the number of sensors and measurement points: Beyond capacity, the number of sensors connected to the temperature control cabinet matters just as much. By Tân Long's technical standard, every room in a cold store needs at least two sensors: one at the evaporator return air inlet and one at the centre of the room. For storage areas above 1,000 m², our engineers recommend additional sensors at the points furthest from the evaporator. This lets the temperature control cabinet detect thermal dead zones promptly, so the goods are stored under uniform conditions.
- Tân Long's technical consultation process: At Tân Long, the process of specifying a temperature control cabinet always begins with an analysis of the floor plan and a detailed equipment list. Our engineering team reviews the number of input and output points (I/O), confirms the communication protocol suits the peripheral devices, and selects a configuration that gives the client's project both room to grow and absolute accuracy.
Installing and operating a temperature control panel
Installing a temperature control cabinet correctly is the decisive factor in the service life and stability of the whole industrial refrigeration system. The panel location must be surveyed carefully and kept well away from large heat sources such as boilers or unshielded compressor packages. The installation area must also be free from heavy vibration, with at least 500 mm of clear space either side and above the panel for heat dissipation and future maintenance.
One particularly important point when running signal wiring for a temperature control cabinet is that dedicated shielded cable must be used. It must run in its own conduit, completely separate from the power cabling. The reason is that electromagnetic interference (EMI) from inverters and refrigeration compressor motors can seriously corrupt the temperature reading if the signal cable runs parallel and close to power cable. Tân Long's internal rules require a minimum separation of 300 mm between signal and power cable along the entire route.
Once mechanical assembly is complete, commissioning temperature control cabinet is carried out methodically through the following steps:
- Check the full wiring diagram and all equipment terminations.
- Verify every input and output point (I/O) in practice.
- Load the operating program into the PLC control panel.
- Run a simulation to test the fault scenarios.
- Run the whole cold store system as a cold run.
Commissioning properly lets Tân Long's engineers find and fix 80% to 90% of programming or wiring errors early. That means the temperature control cabinet is in perfect working order at handover, giving the client complete confidence.
Scheduled maintenance of a temperature control panel
Servicing an industrial temperature control cabinet every 6 months is mandatory to maintain accuracy and prevent unexpected faults. The standard maintenance procedure covers: cleaning dust from inside the panel with dry compressed air, checking and retightening all wiring terminations, measuring insulation resistance to confirm it is at least 1 Megohm, and recalibrating the sensor system.
In cold, damp conditions, PT100 sensors tend to drift by 0.1°C to 0.3°C after around 12 months of continuous operation. For cold stores holding pharmaceuticals or food for export, annual sensor calibration is mandatory. Instruments fitted to the temperature control cabinet must carry a calibration certificate from a VILAS-accredited body, for both legal compliance and food safety.
Tân Long does not only supply off-the-shelf products — we manufacture and install fully integrated PLC control panels and SCADA control panels built to each project, so the control logic matches the actual equipment on site exactly, temperature control cabinet from the refrigeration compressor through to the evaporators.
With more than 20 years of experience, Tân Long has successfully delivered temperature control cabinet systems for a series of large seafood processing plants in Soc Trang, Ca Mau, Nghe An and across the Mekong Delta. Large NH3 refrigeration systems above 500 kW at leading companies such as Kyokuyo Vina Foods, Lotte F&G Vietnam and Frescol Tuna Vietnam all rely on temperature control cabinet solutions designed and installed by Tân Long.
Contact Tân Long's engineering team for advice on the temperature control cabinet best suited to your project's capacity and technical standards.
Frequently asked questions about temperature control panels
Are a temperature control panel and an electrical control panel the same thing?
Electrical control panel is the general term for equipment that distributes and controls power for a system. A temperature control panel is an electrical control panel programmed specifically to manage a temperature control loop, with sensors, a PLC or SCADA, and an HMI operator interface added. Every temperature control panel is an electrical control panel, but not every electrical control panel controls temperature.
How do PLC and SCADA differ in temperature control?
The PLC is the hardware that processes control logic directly on site, in real time, responding within milliseconds. SCADA is the software system that supervises and collects data from several PLCs, displays plant-wide status on a central screen, stores history and generates reports. In industrial refrigeration the PLC does the actual controlling while SCADA provides overall supervision. The two layers complement each other; neither replaces the other.
Can a single-loop temperature controller replace a PLC?
For a single-room cold store with a compressor below 30 kW (40 HP), a single-loop controller such as the Autonics TC4 is enough for basic temperature control. However, a single-loop controller cannot manage a starting sequence, does not protect the compressor on pressure, and cannot integrate with a plant SCADA system. As system capacity grows or equipment is added, a PLC becomes necessary.
What does a PLC temperature control panel cost for a 500 m² cold store?
A PLC control panel for a 500 m² (5,382 ft²) cold store with 2–3 rooms runs from 80 million to 200 million dong depending on the PLC brand (Siemens, Mitsubishi, Schneider), the number of I/O, whether an HMI is included, and the SCADA connectivity required. That represents around 5%–8% of the total refrigeration system cost for a store of that size. Contact Tân Long for an accurate quotation based on your actual project.
Related pages
- Standard maintenance process for industrial control cabinets
- IoT applications in cold storage management: the optimal solution for
- How to use cold storage temperature controller in simple detail
- Cold storage temperature and humidity sensor
- control cabinets for refrigeration systems
Is your business in need of a survey, upgrade, or new design for your industrial refrigeration system?
With over 18 years of practical experience leading more than 29 major national projects, Tan Long's team of HVAC engineers is committed to providing accurate thermal load calculations, optimizing the COP efficiency coefficient, switching between natural refrigerants NH3/CO2, and saving 20–30% in operating electricity costs.
Engineer Nguyen Toan Thinh (Technical Director)
With over 18 years of practical experience in directing, consulting, designing, and constructing heavy industrial refrigeration systems, ASRS automated warehouses, and IQF freezing systems across more than 29 major national projects.
