bonitron M3460UC, Customer Reference Manual

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User’s Manual
45
7.
A
PPENDICES
7.1. M3460 I
NSTALLATION
C
ONSIDERATIONS
There are several things to take in to account when backing up a drive system. The
M3460 is designed to back up the power section of an AC drive and, does so within
the DC link of the drive.
DANGER!
F
OR SYSTEMS THAT HAVE BACKUP STORAGE SYSTEMS
,
SUCH AS CAPACITORS
OR BATTERIES
,
THE
M3460
WILL CONTINUE TO SUPPLY POWER EVEN THOUGH
THE
AC
LINE IS DISCONNECTED
! T
AKE SPECIAL PRECAUTIONS WITH THESE
SYSTEMS TO ENSURE THAT THE POWER CAN BE REMOVED FROM THE SYSTEM
AND LETHAL VOLTAGES DRAINED OR DISCONNECTED FOR SERVICE
!
1. The M3460 must have a DC bus connection directly to the DC bus filter
capacitors within the drives. Connections cannot be made through the braking
terminals or with precharge resistors or DC link chokes between the output of
the M3460 and the DC bus capacitors in the drive. Consult the manufacturers'
documentation or contact Bonitron for further assistance.
2. The drive system may depend on other parts of a larger control system that
requires backup to allow the drive to keep operating, like sensors or external
commands from PLC or relay logic. These systems will need to be backed up
separately with AC UPS systems or logic power backup systems like 24VDC
buffers.
3. Most drives have control and cooling power supplies that are connected to the
DC bus of the drive. These will be backed up by the M3460. Some larger frame
AC drives require consistent AC power to keep operating as they have fans
that get power directly from the AC line. In this case, there may be special
requirements to keep the drive operating.
4. Any AC line outage sensing must be disabled in the drive to keep the drive
from automatically shutting down on a phase loss.
5. Any kinetic buffering option needs to be disabled in the drive. This can cause
interference with the operation of the M3460.
6. If there is ground fault sensing within the drive, this may need to be disabled,
as uneven currents can flow through the AC drive's input bridge causing a trip.
7.2. S
PECIFYING AN
U
LTRACAPACITOR
S
TORAGE
B
ANK FOR
F
ULL
O
UTAGE
P
ROTECTION
W
ITH
M3460R M
ODELS
Bonitron M3460R models can have energy storage devices added to cover complete
outages. This involves adding a capacitor bank with an appropriate charging and
discharging system. Bonitron can source complete capacitor cabinets or individual
capacitors. This section gives some instruction for sizing and specifying these storage
devices.
The process described below is a good way to estimate the capacitor bank required.
Since the discharge characteristic of a capacitor bank with a constant power load is a
nonlinear differential equation, optimizing the capacitor bank selection is an iterative
process. A general estimate of needs must be used to build a capacitor bank and then
the actual values must be cross checked to make sure they are suitable.
There are several steps in the process. The capacitor bank will be comprised of
capacitors connected in series for voltage support, with one or more strings in parallel
to support the energy requirements.