Just something more:
With shunt tripping the coil is energized with a external supply, like tripping batteries, capasitor trip unit, etc.
With series tripping the coil is energized directly from the CT's, meaning that a CT supply a coil. The trip coil is in parallel with a N/C contact of the relay and both then in series with the relay element. Under normal conditions the current will flow through the N/C contact to the relay element, preventing the coil to operate. Under a fault condition, when the relay operate, the N/C contact will open, forcing the tripping coil to operate. Series tripping can just be used with electromecanical relays and each relay element must have its own tripping coil (3ph o/c relay will have three tripping coils)
RCC