bonitron M3460UC, Customer Reference Manual

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User’s Manual
21
4.
O
PERATION
4.1. F
UNCTIONAL
D
ESCRIPTION
The M3460 ride-thru voltage regulator monitors the DC bus of the attached variable
frequency drive (VFD) and provides power in a voltage controlled, current limited
supply directly to the filter capacitor section of the drive above the inverter stage.
During a power quality event the internal DC bus of the VFD drops. When this level
meets the DC bus threshold voltage of the M3460, power is delivered through blocking
diodes to hold up the voltage in the VFD bus. The M3460 regulates and boosts the
input voltage to the drive at a constant voltage.
In standby mode, the M3460 power consumption is minimal.
4.2. M3460UC O
PERATION FOR
F
ULL
O
UTAGE
P
ROTECTION
The M3460UC can be used with an energy storage system to allow for protection
against sags and full outages for up to 2 seconds. This storage is typically double layer
capacitors or ultracapacitors, but can be any DC power source that needs regulation
to attach to the DC input of a variable frequency drive.
In order to use an ultracapacitor storage bank for outage support, the capacitor bank
must be charged with a separate charger, such as the Bonitron M5628, as the M3460
does not have charging capabilities.
Refer to Section 7.2 for general guidelines on sizing a capacitor bank for full outage
protection.
4.3. O
PERATION
M
ODES AND
C
ONFIGURATION
4.3.1. N
ORMAL
O
PERATION
During normal operation, the M3460 will monitor the output DC bus. When the output
DC bus voltage goes below the DC bus threshold voltage, the M3460 will become
active and regulate the output DC bus and attached drive to the DC bus threshold
voltage. As the input voltage drops, more current is required to maintain the same
output power. If the input voltage drops to the point where the required output power
makes the input current higher than the input current limit, the M3460 will operate in
current limit, and the output voltage will drop according to the actual output load
required by the drive.
This mode is activated by the Enable input.
4.3.2. T
EST
M
ODE
The Test mode allows the M3460 to be tested during normal power conditions. In this
mode, the M3460 adjusts the DC bus threshold above the normal DC bus threshold
setpoint. This forces the M3460 to begin sourcing power and driving up the DC bus
voltage of the attached drive. When properly adjusted, the test voltage will be 50-100
VDC higher than the DC bus threshold. This level should not be high enough to
overvoltage the attached drives or cause braking systems to activate. If the drive is
heavily loaded when the test is done, the DC bus may not rise as much as if it were
unloaded.