Under what circumstances is PT usually used in parallel? (Taking the double-bus main wiring configuration as an example)

The condition for automatic PT paralleling is that the busbars are connected together, both sets of PTs are in use, and paralleling occurs automatically if voltage is lost in either set. In the case of manual paralleling, consideration is given to the origin of the two busbars to determine whether paralleling at high voltage is possible; if so, and if one set of PTs needs to be serviced, then paralleling can be achieved using the other set.

This post was last edited by zhaohh3211 on 2010-9-6 12:05. PT parallel: Strong current specialty, terms related to power systems. PT stands for voltage transformer. The busbar PTs are used to measure the three-phase voltages of the busbars; one PT is installed for each of the two busbars. When the PT on busbar I is under preliminary testing, it needs to be taken out of service, while the protection systems associated with busbar I continue to operate (taking into account the low-voltage interlock function). If the protection systems lose voltage, they may malfunction; therefore, the PT on busbar II is needed to maintain the voltage required for the protection systems on both busbars. Hence, it is necessary to connect the PTs in parallel. When paralleling, do it in one step first: close the busbar tie/sectioning switch, and then set the PT paralleling knob to the parallel position. It is necessary to connect the switches on both sides of the busbar/sectioning switch, as well as the switch contacts, in series to the secondary PT parallel circuit, to ensure that the secondary side can be connected in parallel only when the primary side is in parallel. I copied it: L

Reply to 3# Lin Zige: For PT paralleling, a parallel connection is certainly required at some point, but the power supply company requires that we customers not allow long-term ring connections. So, does PT paralleling still have any practical meaning in the current system?

Reply to 4# shiyw2: PT paralleling does not necessarily require the primary circuit to be paralleled as well. If the PT of a certain bus fails (such as the fuse blowing) and needs to be taken out of service for maintenance, the PTs can be connected in parallel so that metering or protection functions can continue to operate.