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5.3.4 RPM CONTROL
The pulse signal from the T09 device in the PM plug is detected by a sensor
and transformed by the electronic central unit into a number of revolutions. The
minimum threshold number of revolutions for the driven member is set up in in
an appropriate regulator included in the electronic central unit, which generates
an alarm condition and causes the motor or drive member to shut down when
the two following conditions pre-set in suitable integrated timers are met:
- Start-up timer (max 60 seconds): it permits to ignore the signals from the
revolution controller for the time set up, during the start-up phase, until
the motor reaches stable operating conditions; afterwards the specific Pre-
alarm Timer takes over.
- Pre-alarm Timer (max 30 seconds): it permits to generate a pre-alarm
condition for the pre-set time. If any rotational slow-down has been
detected under normal operating conditions for longer than the set up pre
alarm time, an alarm signal is released and the motor or drive member are
automatically shut down.
- Remove the causes, which have determined the device triggering due to
overheating.
5.3.5 T09 RESET DUE TO A REDUCTION IN RPM
The alarm released because of a reduction in the number of revolutions entails
no downtime for the reset of this device.
This device is installed upon customer’s request in the standard couplings,
when overloads of the driven end during operation are likely to occur, which may
determine a reduction in the number of revolutions or a start-up overextension
beyond the maximum pre-set time, or in order to avoid the TF fusible plug and/
or the TE Expandable Trip Plug reset after overheating of the hydromechanic
coupling.
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