Sequence

The contact elements for switching capacitors are specifically designed for the operation of power factor correction capacitors (usage category AC-6b).

The capacitors are pre-charged through resistors that reduce the peak current at the contact when the special contact elements CEM_CN are activated. After pre-charging, the main contacts close, allowing the rated current to pass through.

Advantages

• Mounting on DIN rails and mounting panels
• Technical specifications according to IEC 60947-4
• Built-in pre-charge resistors
• High reliability
• Small dimensions
• Standard control voltage: 230V AC

Operating Principle

When a capacitor bank is connected, the capacitors are uncharged, and the system perceives them as a short circuit for a brief period. The inrush current results from this temporary short circuit and lasts, typically, a few milliseconds. It can reach up to 100 times the rated current, which is one of the main causes of reduced capacitor lifespan.

The CEM CN contactor is equipped with snubber resistors that limit the high inrush current during capacitor connection. It features a contact block with an enabled activation, which is activated before the main contacts, thus limiting the inrush current. However, the snubber resistors do not affect the final load, as they disconnect after 5 milliseconds. After this phase, only the capacitors remain connected in parallel with the inductive load, providing proper power factor correction.

Benefits:

• This process extends the lifespan of the capacitors.
• Prevents disturbances in the network.