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Chapter 4 – Electrical Installation
Enable Input
Fibre Optic Link
4-4
By default, the Enable input terminal block X2 (X1 on NBRA-658/659/
669) is short-circuited with a jumper connection, and the enable signal
is present all the time. The signal can be given externally by connecting
a break contact to the terminal block as shown in Figure 4-1. When the
contact opens (enable signal is switched off), the chopper stops
operating, and its relay output gives a fault indication.
The NBRA-658, NBRA-659 and NBRA-669 are equipped with an
internal temperature sensitive switch. In these units, NBRC terminal
block (Enable input) is wired via this switch to a separate terminal block
(X1), shown in the dimensional drawing.
WARNING! The Enable input terminal block is at intermediate circuit
potential when the ACS 600 is connected to the mains. This voltage is
extremely dangerous and may cause serious damage or injuries if the
isolation level and protection conditions for the external switch are not
sufficient. The normally closed switch/contact should always be
properly isolated (over 2.5 kV) and shrouded against contact.
For protection against overheating, resistors with a thermal switch
should be used. (All SACE and SAFUR resistors include a thermal
switch.) The switch should be connected to the enable input of the
chopper: if the resistor overheats, the switch opens and interrupts the
chopper enable input signal. If two resistors are used, the thermal
switches should be connected in series.
The guided light receiver and transmitter on the chopper control board
make the synchronisation of several choppers possible. Refer to
page 3-2.
Installation and Start-up Guide for NBRA-6xx
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