A cold cabinet still needs a complete safety assessment

A freezer can hold its setpoint while another part of the machine is developing a fault. IEC 61010-2-011:2019 covers particular safety requirements for measurement, industrial process-control and laboratory equipment that directly controls a refrigerating system. That system may be built into the equipment or housed separately. Start with the equipment's intended function and its place in the IEC 61010 family.

The second edition, published in 2019, replaced the 2016 edition. It supplements or modifies IEC 61010-1; the particular requirements and the general requirements are used together.

Check the application before choosing the standard

Laboratory refrigerators, freezers and refrigerated cabinets are typical applications. A refrigerated laboratory centrifuge also needs the applicable centrifuge requirements. Equipment with automated analytical functions may bring further particular requirements into the assessment. Simply placing a product in a laboratory does not settle its classification.

Two important exclusions are equipment incorporating a transcritical CO₂ refrigerating system and systems using ammonia (NH₃) as the refrigerant.

Read the 150 g provision correctly

The document details requirements for up to 150 g of flammable refrigerant per refrigerating stage. Above that charge, additional requirements beyond the document's current scope apply. “Per stage” matters: it is not a universal allowance for the whole appliance. A small charge does not, by itself, establish compliance.

Heating and cooling can change the assessment

IEC 61010-2-010 addresses material-heating functions. When heating and refrigeration interact to produce additional or more severe hazards, IEC 61010-2-012 becomes relevant. Without those added hazards, 2-010 and 2-011 can apply to their respective functions. Significant heat introduced by the material under treatment can also affect the selection of 2-012.

Practical example: The condenser fan has stopped

Imagine a refrigerated cabinet whose condenser fan has failed. Its Pt100 or NTC temperature sensor may still report a value close to the setpoint. Conditions elsewhere in the refrigeration circuit can already be deteriorating. Pressure, compressor temperature and electrical hazards are among the issues addressed by the standard. A cabinet temperature reading therefore cannot represent every operating condition.

A PID controller or temperature controller regulates the process during normal operation. A design review should also ask what happens after a disconnected sensor, a permanently energised output or loss of cooling. Alarm, shutdown and restart behaviour must suit the equipment's risks. PTC sensors and thermal protection are possible elements of that wider design; their presence alone does not resolve every fault.

For measurement quality, consider RTD wiring and sensor tolerance classes. For protection, consider sensor location, the actual interruption function and the response to a fault. Accurate sensing cannot substitute for every protective function.

Useful questions for a supplier or design review

Evidence: Does the test report identify the complete model, refrigerant type and charge, standard editions and assessed operating conditions? Approval of one component does not automatically cover the finished assembly.

Installation: Are ventilation clearances, ambient conditions and placement instructions specified? An IP rating describes a particular enclosure protection capability; it does not establish the safety of the refrigeration circuit.

Moisture and interference: Humidity measurement can help explain conditions that encourage condensation. EMC requirements need separate consideration. For an environmental chamber, temperature and humidity performance verification asks another practical question: Does the chamber actually produce the required test environment?

Continue with related topics

References and sources

IEC 61010-2-011:2019 — IEC Webstore
IEC 61010-2-011:2019 — IEC publication preview (VDE Verlag)
IEC 61010-2-012:2019 — IEC Webstore
IEC 61010-2-020:2026 — IEC Webstore