![background image](http://html1.mh-extra.com/html/nidec/5200250/5200250_power-installation-manual_1687772063.webp)
Unidrive M/HS Frame 5 to 6 Power Installation Guide
63
Issue Number: 9
S
P
M
El
Te
UL
list
ing
in
Table 4-7 Minimum resistance values and peak power rating for the braking resistor at 40 °C (104 °F)
For high-inertia loads or under continuous braking, the continuous power dissipated in the braking
resistor may be as high as the power rating of the drive. The total energy dissipated in the braking
resistor is dependent on the amount of energy to be extracted from the load.
The instantaneous power rating refers to the short-term maximum power dissipated during the on
intervals of the pulse width modulated braking control cycle. The braking resistor must be able to
withstand this dissipation for short intervals (milliseconds). Higher resistance values require
proportionately lower instantaneous power ratings.
In most applications, braking occurs only occasionally. This allows the continuous power rating of the
braking resistor to be much lower than the power rating of the drive. It is therefore essential that the
instantaneous power rating and energy rating of the braking resistor are sufficient for the most
extreme braking duty that is likely to be encountered.
Optimization of the braking resistor requires careful consideration of the braking duty.
Select a value of resistance for the braking resistor that is not less than the specified minimum
resistance. Larger resistance values may give a cost saving, as well as a safety benefit in the event
of a fault in the braking system. Braking capability will then be reduced, which could cause the drive
to trip during braking if the value chosen is too large.
The following external brake resistors are available from the supplier of the drive for sizes 5 and 6.
Model
Minimum resistance *
Instantaneous power
rating
Continuous power
rating
Ω
kW
kW
200 V
05200250
19
8.9
8.6
06200330
10
16.9
12.6
06200440
16.4
400 V
05400270
38
17.8
16.2
05400300
22
30.8
19.6
06400350
20
33.8
21.6
06400420
25
06400470
32.7
575 V
05500030
80
12.1
2.6
05500040
4.6
05500069
6.5
06500100
15
64.1
8.7
06500150
12.3
06500190
16.3
06500230
19.9
06500290
24.2
06500350
31.7
* Resistor tolerance: ±10 %. The minimum resistance specified are for stand-alone drive systems
only. If the drive is to be used as part of a common DC bus system different values may be
required. Contact the supplier of the drive for more information.
Summary of Contents for 5200250
Page 110: ...0478 0255 09...