Motor Brake Requirements

Zero, one, or two brakes can be configured under safe brake control SBC (see "SBC (Safe Brake Control)"). The brake must be a fail-safe brake with multiple springs. A fail-safe brake is applied when the 24V brake voltage is removed.

Important notes

External brakes must allow operation at 100% duty cycle at 24V. In case of a failure the brake must be rated for the full current at full time.

 

Brakes are subject to wear. Wear increases by frequency and intensity of use. Avoid overloading the brakes by reducing motor speed with electrical braking before engaging the brakes when possible.

 

When a brake is used to reduce a risk (usage with SBC), it is part of a safety chain. As part of a safety chain, the brake must fulfill the requirements for functional safety depending on the target SIL or PLr.

The brake PFHd value shall not occupy more than 50% of the PFHd value of the whole safety chain. Keep in mind that the PFHd value of a brake depends on frequency of usage. Kollmorgen brakes offer a B10d of >15,000,000 use cycles. For more information, refer to the respective Motor Documentation.

Example:
A use rate nop of 2/h will result in a PFHd of 13.3 FIT.
PFHd = 1 / [B10d / (0.1 * nop)] = 1 / [15 * 106 / (0.1 * 2/h)] = 13.3 FIT

Connection

Configuration

Safety functions can be configured to use SBC (see "SBC (Safe Brake Control)") as part of their fault reaction. You have the option of configuring the fault reaction of a safety function to use:

  • No brake.
  • One brake per axis. For axis 1 use BRAKE1, for axis 2 use BRAKE2. These brake lines are normally pre-wired on the motor cable.
  • Two brakes on a single axis drive. BRAKE1 is normally pre-wired on the motor cable, BRAKE2 is brought out to a separate connector X4.
  • Two brakes on axis 1 of a dual axis drive. BRAKE1 is normally pre-wired on the motor cable, BRAKE2 must be wired across from X2.