4.1 EMC-compliant setup of the machine or plant
The inverter is designed for operation in industrial environments where strong electromagnetic fields are to be expected.
Reliable and disturbance-free operation is only guaranteed for EMC-compliant installation. To achieve this, subdivide the control cabinet and the machine or system into EMC zones:
Inside the control cabinet
● Zone A: Line supply connection
● Zone B: Power electronics
Devices in Zone B generate energy-rich electromagnetic fields.
● Zone C: Control and sensors
Devices in Zone C do not generate any energy-rich electromagnetic fields themselves, but their functions can be impaired by electromagnetic fields.
Outside the control cabinet
● Zone D: Motors, braking resistors
Devices in Zone D generate electromagnetic fields with a significant amount of energy
4.1.1 Control cabinet
● Assign the various devices to zones in the control cabinet.
● Electromagnetically uncouple the zones from each other by means of one of the following actions:
– Side clearance ≥ 25 cm
– Separate metal enclosure
– Large-area partition plates
● Route cables of various zones in separate cable harnesses or cable ducts.
● Install filters or isolation amplifiers at the interfaces of the zones.
Control cabinet assembly
● Connect the door, side panels, top and base plate of the control cabinet with the control cabinet frame using one of the following methods:
– Electrical contact surface of several cm² for each contact location
– Several screw connections
– Short, finely stranded, braided copper wires with cross-sections ≥ 95 mm² / 000 (3/0) (‑2) AWG
● Install a shield support for shielded cables that are routed out of the control cabinet.
● Connect the PE bar and the shield support to the control cabinet frame through a large surface area to establish a good electrical connection.
● Mount the control cabinet components on a bare metal mounting plate.
● Connect the mounting plate to the control cabinet frame and PE bar and shield support through a large surface area to establish a good electrical connection.
● For screw connections onto painted or anodized surfaces, establish a good conductive contact using one of the following methods:
– Use special (serrated) contact washers that cut through the painted or anodized surface.
– Remove the insulating coating at the contact locations.
Measures required for several control cabinets
● Install equipotential bonding for all control cabinets.
● Screw the frames of the control cabinets together at several locations through a large surface area using serrated washers to establish a good electrical connection.
● In plants and systems where the control cabinets are lined up next to one another, and which are installed in two groups back to back, connect the PE bars of the two cabinet groups at as many locations as possible.
4.1.2 Cables
Cables with a high level of interference and cables with a low level of interference are connected to the inverter:
● Cables with a high level of interference:
– Cable between the line filter and inverter
– Motor cable
– Cable at the inverter DC link connection
– Cable between the inverter and braking resistor
● Cables with a low level of interference:
– Cable between the line and line filter
– Signal and data cables
Cable routing inside the cabinet
● Route the power cables with a high level of interference so that there is a minimum clearance of 25 cm to cables with a low level of interference. If the minimum clearance of 25 cm is not possible, insert separating metal sheets between
the cables with a high level of interference and cables with a low level of interference. Connect these separating metal sheets to the mounting plate to establish a good electrical connection.
● Cables with a high level of interference and cables with a low level of interference may only cross over at right angles:
● Keep all of the cables as short as possible.
● Route all of the cables close to the mounting plates or cabinet frames.
● Route signal and data cables - as well as the associated equipotential bonding cables - parallel and close to one another.
● Twist incoming and outgoing unshielded individual conductors. Alternatively, you can route incoming and outgoing conductors in parallel, but close to one another.
● Ground any unused conductors of signal and data cables at both ends.
● Signal and data cables must only enter the cabinet from one side, e.g. from below.
● Using shielded cables for the following connections:
– Cable between the inverter and line filter
– Cable between the inverter and output reactor or sine-wave filter
Routing cables outside the control cabinet
● Maintain a minimum clearance of 25 cm between cables with a high level of interference and cables with a low level of interference.
● Using shielded cables for the following connections:
– Inverter motor cable
– Cable between the inverter and braking resistor
– Signal and data cables
● Connect the motor cable shield to the motor enclosure using a PG gland that establishes a good electrical connection.
Requirements relating to shielded cables
● Use cables with finely-stranded, braided shields.
● Connect the shield to at least one end of the cable.
● Attach the shield to the shield support directly after the cable enters the cabinet.
● Do not interrupt the shield.
● Only use metallic or metallized plug connectors for shielded data cables.
4.1.3 Electromechanical components
Surge voltage protection circuit
● Connect surge voltage protection circuits to the following components:
– Coils of contactors
– Relays
– Solenoid valves
– Motor holding brakes
● Connect the surge voltage protection circuit directly at the coil.
● Use RC elements or varistors for AC-operated coils and freewheeling diodes or varistors for DC-operated coils.