Brake Transistor Monitor - KEB COMBIVERT F5 Operation Manual

Brake Transistor Monitor

1.2.14. Brake Transistor Monitor
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The brake transistor monitor circuit monitors the brake transistor circuit and
indicates to the elevator controller that a shutdown of the system is required
in the event of a brake transistor failure.
Monitor Circuit
The brake transistor monitor circuit is part of the braking resistor circuit and
monitors the brake transistor to confirm the transistor is switching correctly.
If the brake transistor fails, the monitor circuit opens terminals K1/K2. It is
the responsibility of the OEM (elevator control manufacturer) to monitor
terminals K1/K2 and to bring the system to a safe halt in the event of a
brake transistor failure.
The K1/K2 terminals are a normally closed contact and shall be connected
either to a line contactor to disconnect the drive from the high voltage
supply, or to a DC contactor to disconnect the brake resistor from the drive.
The DC contactor may be either single pole or double pole. If single pole
the contact should be wired in series with the positive terminal of the brake
resistor.
Through the K1/K2 and connected power contactor, the source of energy
is removed from the brake resistor in the event of a brake transistor failure,
thereby preventing dangerous overheating of the brake resistor.
Contactors are not included with the drive and must be purchased
separately. Contact KEB for assistance on selecing the right contactor
option for your application. See below for sizing.
No Monitor Circuit
On drives without the brake transistor monitor (K1/K2) contacts, a
temperature sensor shall be connected to the brake resistor to provide a
warning of brake transistor failure. If the brake transistor fails, the brake
resistor begins to overheat, thus opening the normally closed temperature
sensor on the brake resistor.
The temperature sensor shall be connected to either line contactor to
disconnect the drive from the high voltage supply, or to a DC contactor
to disconnect the brake resistor from the drive. The DC contactor may be
either single pole or double pole. If single pole the contact should be wired
in series with the positive terminal of the brake resistor.
Component Rated Values
The line contactor shall be rated for the rated main line voltage and have an
AC-1 current rating not less than the expected FLA of the elevator drive.