GB - 13
Installation and Connection
3.3.6 Connection of a braking resistor with fire prevention
With input rated voltage of 480 Vac no braking resistor shall be connected at
control type "BASIC". The operating threshold of the braking resistor (Pn.69)
must be adjusted at least to 770 Vdc for all other controls (see annex).
At defective braking transistor this circuit prevents against overheating and fire. The bra-
king resistor overheats and opens the OH terminals with defective braking transistor. The
OH terminals open the holding circuit of the input contactor, so that the input voltage is
switched off in error case. An error in inverter is released by opening the auxiliary contacts
13/14 of K3 and the modulation is switched off. Regenerative operation is also secured by
the internal fault disconnection. The input must be programmed and inverted to "external
error". Automatic restarting after cooling of the braking resistor is prevented by the self-
holding circuit of K3.
If the PTY evaluation of the motor at terminals T1/T2 is not used, these terminals
can be used instead of the programmable input. The temperature input must be
operated in PTC mode.
Picture 3.3.6
Braking resistor with fire prevention
T1 T2
L1
L2
L3
K3
2
U V W
L1 L2 L3
1
4
3
6
5
12
11
14
13
G1
R1
++
PB
OH1
OH2
I1
0V
PE
F
R2
+24V
S2
I1
G1
K3
GND
S1
K3
11
12
H1
0V
R1
OH2
OH1
K3
13
14
K3 Line contactor with auxiliary
contacts
H1 Tripping control
S1 Push-bottom switch for switch on
R1 Braking resistor with temperature switch
S2 Emergency stop circuit braker for
switch off
R2 PTC sensor e.g. of the motor
G1 Inverter with programmable input I1
