Auxiliary Components; Main Contactor And Precharge Circuit; Digital Outputs From Dragon8; Key Switch Fuse F2 - Sevcon Dragon8 Applications Reference Manual

Auxiliary components

Main Contactor and Precharge circuit

The Dragon8 range of controllers incorporate both a battery switch and a main DC-link capacitor pre-
charge circuit. This helps simplify system design and reduce system costs.

Digital Outputs from Dragon8

The digital outputs can provide up to 2A each and can be used for various purposes (e.g. lamps, relays,
contactors). But users should be aware that these outputs are powered from
If the key-switch is turned off the contactors would open immediately even if the motor was turning.
See Figure 13 for a circuit diagram showing the internal components.
The outputs are short-circuit proof and thermally protected, but users should be aware that if the flyback
diode is connected in parallel with the load inductor, the controller will be damaged in the event of
reverse battery.
Figure 13 - Digital Output Schematic
Note the following:
•
The digital output is ON/OFF only
•
The load should be referred to the logic ground
•
The load must not have a parallel diode, as this would violate the reverse battery protection

Key switch fuse F2

Use a fuse rated for the sum of the analogue output drive currents plus 2A for internal circuits.

Motor speed sensor (AB encoder)

A 6-wire connection is provided for open-collector quadrature pulse encoder devices. These types of
encoder are optimized for accurate speed measurement, required for efficient control of induction motors.
32
KL15/KL30 (key-on supply).