Baldor MicroFlex e100 - Regeneration Resistor (Dynamic Brake Resistor); Regeneration Capacity

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Basic Installation 3-23MN1942
3.6 Regeneration resistor (Dynamic Brake resistor)
An optional external regeneration resistor may be required to dissipate excess power from the
internal DC bus during motor deceleration. The regeneration resistor must have a resistance of
at least 39 Ω, an inductance of less than 100 μH, and a minimum power rating of 44 W. Care
should be taken to select the correct resistor for the application - see section 3.7. Suitable
regeneration resistors are listed in section A.1.5. The regeneration resistor output is conditionally
short-circuit proof.
Electrical shock hazard. DC bus voltages may be present at these terminals.
Use a suitable heatsink (with fan if necessary) to cool the regeneration resistor .
The regeneration resistor and heat sink (if present) can reach temperatures in
excess of 80 °C (176 °F).
Regeneration
resistor
STAR
POINT
Earth/ground outer shield,
using 360° conductiv e
clamp connected to
enclosure backplane
Figure 11 - Regeneration resistor connections
3.6.1 Regeneration capacity
The regeneration capacity of the MicroFlex e100 can be calculated from the following formula:
where the Regen switching threshold is 388 V. This gives the following typical values:
MicroFlex e100
c
a
t
a
l
o
g
n
u
m
b
e
r
Regeneration capacity (J)
catalog numbe
r
DC bus
cap acit ance (μF)
115 VAC supply 230 VAC supply
MFE230A003 560 34.7 12.5
MFE230A006 1120 69.4 25
MFE230A009 1680 104.2 37.6
Table 5 - Regeneration capa c ity
W ARNING
E = 0.5 × DC bus capacitance ×

(
Regen switching threshold
)
2
−

2

× Supply voltage

2
