Thyristor stack controller makes retrofitting easy
An external thyristor stack controller, called the PLXD, has been introduced by Sprint Electric. Supplied with the latest field bus protocols, the controller can be designed into a new installation or easily retrofitted to an existing thyristor power stack where the control electronics need updating or require adding into a field bus topography network.
Possessing the functionality of Sprint Electric’s PLX DC drives range, the PLXD thyristor stack provides gate drive pulses for driving user supplied pulse transformers with primary pulse current up to 1.5A. There are terminals to accept an externally generated isolated armature current signal, field signal, thermal heatsink sensor switch, and high voltage armature voltage feedback. The unit also provides a +24 V supply for the gate drive pulse transformers that is short circuit protected.
The following stack configurations can be driven by the PLXD: 6 pulse 2 Quadrant bridge (6 thyristors), or 2 bridges in parallel (12 thyristors), as well as 6 pulse 4 Quadrant regenerative anti-parallel bridge (12 thyristors). Extra stacks can be used in parallel within the gate drive capability, with all customer control terminals being the plug-in screw terminal variety. The PLXD can be used with up to 690V AC on its 3 phase auxiliary supply inputs (EL1/2/3), while the external stacks can be of higher voltages if required. The armature voltage inputs can monitor up to +/-1000 V DC. There is an integral motor field bridge with independent single phase AC supply inputs (EF2/3) for controlling fields up to 32A. The internal field bridge supply input voltage rating is 480V AC. Provision is made for providing an external field feedback signal and controlling an external field with user supplied primary gate pulse transformer drivers.