bonitron M3534B, Customer Reference Manual

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M3534R 20A
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the maximum input voltage for the M3534R, then the minimum series string
combination should be used in parallel and the process repeated.
7.5. D
IODE
S
HARING WITH A
B
ONITRON
R
IDE
-T
HRU
Diode sharing is used to decrease the cost of implementing regeneration, braking, or
Ride-Thru modules to existing drive systems that are not common bussed. The use of
diodes prevent drive busses from “back feeding” each other, by allowing energy to pass
one way only.
For regenerative applications the energy is allowed to pass from the drive bus to the
regen or resistive braking module, but is blocked from passing from regen or brake
module to the drive.
For Ride-Thru applications, the energy is allowed to pass from the Ride-Thru module
to the drives, but is blocked from the drives to the Ride -Thru. Figure 6-9 is a block
diagram example of a Ride-Thru / diode application.
Below are some basic guidelines for using diodes in this manner for 50% sag Ride-
Thru applications:
1. Drives should have equivalent DC bus levels as would be found on equal size
drives of a common manufacturer. (see Figure 7-2)
b.
If positive and negative busses are different potentials, the standard
precharge may overheat and the Ride-Thru may be constantly active.
2.
Drives should be on same AC feeder in same cabinet or close proximity.
a.
Different feeds may have different potentials and may cause circulating
currents or ground faults.
3. Drives should have a common line choke or harmonic filter
a.
Any input filter should be common to all drives on a single Ride-Thru. (see
Figure 7-1)

The use of individual input harmonic filters or line chokes can cause
unequal potentials with respect to earth.
4. Ride-Thru connection should be downstream of any input line filter.
a.
Input line filters cause lower DC bus levels. If a Ride-Thru is placed
upstream, the Ride-Thru DC bus will be higher than the drive bus, and
energy will flow full time out of the Ride-Thru module which may cause
constant activity and overheating.
b.
Special SCR input models are available for applications where a
downstream connection point is not available.

It may be necessary to lower the threshold for these applications.
5. Ground Fault sensing should be done upstream at common point of line
connection, upstream of line filter if used.