￭ Mechanical brake control
A mechanical brake can be used for holding the motor and driven machinery at zero
speed when the drive is stopped, or not powered. The brake control logic observes the
settings of parameter group 44 Mechanical brake control as well as several external
signals, and moves between the states presented in the Brake state diagram on page
77. The tables below the state diagram detail the states and transitions. The timing
diagram on page 79 shows an example of a close-open-close sequence.
The mechanical brake control logic operates on a 10 ms time level.
Inputs of the brake control logic
The start command of the drive (bit 5 of 6.16) is the main control source of the brake
control logic. An optional external open/close signal can be selected by 44.12. The two
signals interact as follows:
•
Start command = 1 AND signal selected by parameter 44.12 = 0 → Request brake
to open
•
Start command = 0 OR signal selected by parameter 44.12 = 1 → Request brake
to close
Another external signal – for example, from a higher-level control system – can be
connected via parameter 44.11 to prevent the brake from opening.
Other signals that affect the state of the control logic are
•
brake status acknowledgement (optional, defined by 44.7),
•
bit 2 of 6.11 (indicates whether the drive is ready to follow the given reference or
not),
•
bit 6 of 6.16 (indicates whether the drive is modulating or not),
• optional FSO-xx safety functions module.
Outputs of the brake control logic
The mechanical brake is to be controlled by bit 0 of parameter 44.1. This bit should be
selected as the source of a relay output (or a digital input/output in output mode) which
is then wired to the brake actuator through a relay. See the wiring example on page 80.
The brake control logic, in various states, will request the drive control logic to hold the
motor, increase the torque, or ramp down the speed. These requests are visible in
parameter 44.1.
76 Program features
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