The TVD is available in two power levels. It can be used to supply power to main and servo drives having an overall continuous mechanical power output of either 6 kW or 12 kW. The TVD can be connected directly to 380 … 460 V, 50 … 60 Hz three-phase power systems without the need for transformers. A power protection circuit is built in to isolate the drive equipment from the AC power system. A soft-start circuit in the TVD prevents high inrush current spikes so that the line connection protection devices do not need to be oversized. Line connections can be protected by circuit breakers or slow-blow fuses. Semiconductor type circuit protection devices are not needed. The TVD DC bus voltage is regulated so that variations in the line voltage have no effect on drive dynamics. In many cases this permits higher drive speeds to be achieved. The TVD is always operated with a line filter. Thus, it causes virtually no line reaction. The NAM line conditioning module makes the TVD and the necessary filter components easy to install. When the drives are running in generator mode, the regenerated energy is absorbed by a bleeder resistor. The TVD may be combined with the TBM 1.2 Auxiliary Bleeder Module to increase the continuous and peak regenerated power rating. TCM 1 Auxiliary Capacitance Modules can be connected to the TVD. When the drives are being braked, the drive energy is stored in the DC bus so that it can be reused for acceleration. Heat losses in the enclosure and energy consumption are therefore minimal. Approximately 30 Ws can be stored per mF auxiliary capacitance. A dynamic braking feature is provided on the TVD so that motors whose field is produced by a permanent magnet can even be braked if a fault occurs in the drive electronic system. If there is trouble in the drive electronic system or in the system installation (feedback line), the dynamic braking feature is activated by the ready-state contact (Bb) on the TVD, causing the drives to brake to a stop. The signal voltage is supplied to all drives via a wire-ribbon cable. In the event of a power failure, the electronic circuitry is supplied with power from the DC bus. The drives can therefore be stopped under velocity or position regulation when power failures occur. The line connections for supplying power to the drives and to electronic circuits are jumpered on the unit. Thus, an additional line connection for supplying power to the electronic circuits is not required. The TVD is equipped with an extensive range of monitoring functions. It communicates with the drives by means of the wire-ribbon cable. Monitored parameters include: motor feedback, current and temperature of the drives, the load on the bleeder resistor, and line voltage. If trouble is encountered, the ready-state contact on the TVD causes the power supplied to the drives to be shut off immediately. LED displays provide for rapid trouble shooting.