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190
Apparatus control
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The purpose of the reservation and selection is to prevent double operation, either in the
bay itself or in the complete station. For an operation in the bay, the reservation part al-
ways reserves the own bay. The engineer can include or exclude the part that reserves
other bays.
The selection and reservation function consists of four parts:
1. Reservation of the own bay
2. Requesting reservation of other bays and handling of the acknowledgement signals
3. Replying to reservation requests
4. Permitting selection of apparatuses, depending on reservations
The selection and reservation function has two ways of starting. It starts when a request
select signal is set in the own bay or when it receives a request for reservation from an-
other bay.
The basic part of the reservation function is the reservation of the own bay. When the
reservation is made, no acceptance of selections from other apparatuses can occur until
all selection requests and reservations are cancelled.
Reservation of the other bays can also be made. A request for reservation is sent to these
other bays. All bays should respond with an acknowledgement that they have reserved
the own bay for operations. After reception of these signals, the reservation is consid-
ered successful and selection can proceed.
To prevent that a reservation is not reset when the reserve request becomes invalid, the
reservation in the own bay and the acknowledgement to the other bays are cancelled
when the cancel reservation timer has expired. The engineer should set this time to the
operating time of the slowest not hand driven disconnector.
One timer supervises the reservation. If the time until a successful reservation is too
long, the command sequence is stopped and an error message is generated.
It is possible to ignore failing reservation of other bays, if the operator wants to operate
the apparatus. There is an override signal for this purpose.
Blocking of the reservation function is possible. With an override, the blocking of res-
ervation on requests from inside the bay can be bypassed.
The reservation method is briefly explained in figure 82 and follows these steps:
1. Select close/open from the station HMI
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