22
EATON
www.eaton.com
Instruction Booklet
IB020003EN
Effective January 2021
AMPGARD RVSS
Reduced Voltage Soft-Starter
User Manual
•
Load side Phase to Phase fault,
•
High di/dt from Load Side long shielded cable, installed surge capacitor or power
factor correction capacitor fault, and
•
Open Phase fault.
The battery of tests takes approximately 0.6 seconds to complete.
When the tests are complete and no faults are detected, the start
sequence continues. If any faults are detected, the start sequence
is aborted and a fault message is displayed.
shows the
Pre-Start check sequence and the fault states tested.
A generic FCODE 4 indicates a Pre-Start Check fault. Further
information is available with the Pre-Start Sub-Code reason. Refer to
the
section for further information.
2.2.5 Overload
Motor overload is a thermal bucket I
2
x
t function. The bucket size is
calculated from motor Locked Rotor Amps and Locked Rotor Time
(see
). Heat accumulating in the motor windings
is estimated based upon the current delivered to the motor and
the time over which the current was flowing. This heat estimate
is displayed on an MUM screen and compared to a set thermal
bucket size. When the estimated motor accumulated heat equals the
calculated maximum allowed, an Overload fault occurs.
The I
2
x
t calculation starts accumulating above 115% RMS current
with service factor (SF) = 1.00 and above 125% RMS current with
SF = 1.15. The motor cooling is calculated based upon the Cool Time
Constant when operating at less than these current values.
2.2.6 Incomplete sequence
The RVSS performs a start sequence using SCRS to provide variable
voltage with current limit. After commissioning, the system starting
behavior is known and should be repeatable. A start sequence
taking longer than that observed after commissioning can be an
indication of problems with the electrical system, RVSS, motor or
connected load and should be addressed. During commissioning,
the RVSS is programmed with the anticipated time to start, based
upon the electrical and mechanical system components. If a start
takes longer to complete than the anticipated time to start, an
Incomplete Sequence is declared, to protect from a Stall or Blocked
Rotor condition.
Figure 12. Pre-start checks sequence
2.2.7 RVSS Overtemperature
Each SCR truck power-pole heat sink assembly has a positive
temperature coefficient (PTC) thermistor mounted on it to monitor
and transmit the heat sink temperature back to the I/O Board. The
DSP monitors these temperatures and declares a fault if the heat
sink temperature limit is exceeded.
This PTC temperature is also used with a lookup table to derate
the truck electronic overload bucket size when frequent starts are
occurring, to protect the SCRs from excessive temperatures.
2.2.8 Starts limit exceeded
The controller has a settable parameter, "Allowed Starts/hr," that
determines how many starts will be allowed per hour of operation.
This setting is separate from the "Time Between Starts" setting, that
allows for motor cooldown between starts. It is also separate from
the BackSpin Inhibit condition. When this parameter has a non-zero
allowed starts per hour setpoint, the controller will generate a fault
and a fault message, "Starts limit exceeded," if that limit is exceeded.
2.2.9 Undervoltage
If at any time the line voltage supplied to the AMPGARD RVSS is too
low for reliable operation, the system faults, an alarm message is
displayed, and the system is prevented from operation until the fault
trip is reset and suitable line voltage is restored.
This may occur during high-demand starting with weak line voltage
sources where sagging voltage conditions are likely.
2.2.10 Overvoltage
If at any time the line voltage supplied to the AMPGARD RVSS
exceeds levels acceptable for reliable operation, the system faults,
an alarm message is displayed, and the system is prevented from
operation until the fault trip is reset and suitable line voltage is
restored.
PLL angle
Half cycle counter
Ph A+ firing signal
Ph A- firing signal
Ph B+ firing signal
Ph B- firing signal
Ph C+ firing signal
Ph C- firing signa
l
SCR OC fault
checking
PFC fault
checking
Ph-to-Ph fault checking
System (Ground)
fault checking
SCR SC
fault
checking