MainsPro G99TT 1.0.0 Global Guide
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9.2.1 External trip
In case that a specific protective function is requested and this function is not supported in MainsPro
G99TT, it may be provided in an external device. Wire the output of this device to Ext1 (page 63) orExt2
(page 63) to allow tripping by this external device.
Use the External trip also for forced disconnection of the generator if such command is for example
evaluated in a superior system or transmitted through remote communication device.
External trip functionality may be also used for intertripping method of protection system topology. This
method is required by the mains operator for bigger generators.
9.2.2 Fault reset
Use this switch in case that complex conditions are to be evaluated before the generator is allowed to be
connected back to mains. These conditions may be processed in an external system and the result may
be sent to this switch.
Provided the MainsPro unit is inside a locked cabinet, an external key switch wired to this input provides a
convenient way of restricting the Fault reset (page 32) operation to be performed by an authorized
personnel only.
Remote fault reset via GSM communicator may also be a useful feature for the remote sites.
9.2.3 Alternative settings
Alt Settings (page 63) binary switch may be used in case that a specific setting of the protection relay is
required by the mains operator when exceptional conditions occur. After deactivation, the unit immediately
switches to the default groups of setpoints.
9.2.4 Disable
The Disable (page 63) switch can be used to block the MainsPro G99TT protective functions, e.g. in case
that the generator is not running in parallel operation with mains, or any other blocking conditions are
fulfilled.
9.2.5 CB Feedback
The CB Feedback (page 63) switch is used to confirm that a circuit breaker opened on a command
issued by MainsPro G99TT. Any time some protective function is activated and a trip is issued,
deactivation of this binary input is expected. If the feedback does not confirm opening of the CB, additional
back-up trip BakTrpPer (page 69) and BakTrpImp (page 70) will be issued after adjustable time delay
BakTrpDel.
9.3 Counters
Keeping a track of the most frequent trips may provide valuable information for the generator as well as
distribution network operator. Use the counters indication on the Measurement screens (page 24) for
keeping track of the most frequent failures detected in the point of your connection. For example, in case that
the MainsPro G99TT counters show significantly higher rate of a certain failure types (e.g. overvoltage or
Vector shift), it may be a good signal to perform a detailed evaluation of the voltage quality in the point of
connection or start discussions with the DNO to allow for wider limits of the protection setting to minimize
down-times of the generator.
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