General safety information for frequency converters

1. Purpose and limits of this information

This page identifies recurring hazards associated with industrial frequency converters and points qualified personnel to matters that must be clarified before work begins. It is general, manufacturer-independent supplementary information only.

It does not account for the exact order number, voltage and power class, hardware or firmware version, installed options, supply and earthing system, motor, braking equipment, machine, safety architecture, environment or local rules.

No terminal assignment, conductor size, fuse rating, protective device, tightening torque, discharge time, parameter value, motor approval, EMC measure or interchangeability statement may be derived from this page.

2. Identify the exact device and obtain the applicable documents

Before connection or any other work, identify the complete manufacturer and order number, all nameplate data, voltage class, ratings, hardware and firmware version, installed options and accessories.

Use only the operating, installation and safety documentation that applies to that exact version, together with the circuit diagrams and safety documentation for the specific machine or installation. Documentation for a similar model, older generation or different power class must not be transferred without verification.

3. Qualified and authorised personnel only

Connection, modification, testing, parameterisation, commissioning, troubleshooting, maintenance and repair may be performed only by personnel who are qualified for the specific task, authorised by the operator and familiar with the machine or installation.

The operator is responsible for the site-specific risk assessment, work planning, selection of suitable personnel, protective measures, required inspections and safe operation under the laws and rules applicable at the place of use.

4. Dangerous voltages and stored energy

Stopping the drive from a keypad, controller, fieldbus, enable input, emergency-stop device or Safe Torque Off does not establish an electrically safe condition. Supply terminals, DC-link terminals, motor connections, braking equipment, external control supplies and coupled DC links may remain live.

Observe the manufacturer-specified discharge time. Then verify absence of voltage with suitable equipment at every relevant point. Indicator lamps, displays and software status are not proof that the equipment is de-energised.

5. Isolation and prevention of unexpected restart

• Identify and isolate every energy source, including external and regenerative supplies.
• Secure isolating devices against reconnection and apply the site lockout/tagout procedure.
• Verify absence of voltage and discharge stored electrical energy.
• Secure rotating parts, suspended loads and stored mechanical or pneumatic energy.
• Prevent remote, automatic or time-controlled restart before access is permitted.

6. Installation, environment and cooling

The enclosure, mounting orientation, clearances, ventilation, cooling-air quality, contamination class, temperature, humidity, altitude, vibration and protection against conductive dust or moisture must match the exact manufacturer requirements.

Blocked airflow, incorrect mounting, missing covers, damaged fans, loose heat sinks or operation outside the specified environment can cause overheating, fire or premature failure. Do not energise a device with visible mechanical, contamination, moisture or overheating damage until it has been assessed by qualified personnel.

7. Supply, motor, brake and DC-link connections

Verify the supply system, rated voltage, short-circuit capability, protective devices, line reactors, filters, motor data, cable type and length, braking resistor or regenerative unit, and any shared DC-link arrangement against the exact documentation and project design.

Interchanging supply and motor terminals, using an unsuitable motor or brake component, or connecting an incompatible DC-link device can destroy equipment and create severe electrical and mechanical hazards.

8. Protective earthing and EMC measures

Protective-earthing conductors, bonding, shield terminations, cable routing and EMC components are safety-relevant. Their design must account for leakage currents, fault currents, high-frequency interference and the applicable supply system.

Do not infer a protective measure from cable colour, enclosure contact or an existing installation. Verify continuity, conductor suitability and the effectiveness of the complete protective arrangement before operation.

9. Parameterisation and motor data

Existing parameters, memory cards and copied datasets must be treated as unverified until they have been matched to the exact converter, motor, encoder, brake, machine and safety design. A factory reset does not create a safe or usable application configuration.

Motor identification, autotuning and test functions can energise the motor and cause movement. The working area must be secured, loads controlled and the manufacturer's procedure followed before such functions are started.

10. Safety functions are not automatically validated

The presence of terminals or labels such as STO, SS1 or another safety function does not prove that the function is correctly designed, wired, parameterised or effective in the particular machine.

The operator must validate the complete safety function, including sensors, logic, wiring, converter, motor, brakes, mechanics and stopping behaviour, in accordance with the machine risk assessment and applicable requirements.

11. Inspection and controlled commissioning

• Document identity, condition, wiring, earthing, protective devices and parameter sources.
• Perform the electrical and functional inspections determined by the qualified person before installation and first use.
• Use a safeguarded test environment and begin with the lowest practicable energy and speed.
• Keep personnel outside hazardous areas and provide an effective means of stopping and isolating the system.
• Record results and release the equipment only after all deviations have been resolved.

12. Maintenance, repair and stop conditions

Repairs, replacement of power components, insulation work and work on the DC link require suitable expertise, equipment and a manufacturer-compatible process. Protective covers, seals and safety-relevant parts must not be bypassed or improvised.

If the exact product version cannot be identified, the applicable manufacturer documentation is unavailable, or there is doubt about condition, assignment, compatibility or connection requirements, the component must not be connected, energised, released or commissioned.