The Solcon HRVS-DN is a heavy duty medium voltage soft starter for standard medium
voltage three-phase squirrel cage induction motors. Output current
spans 60 to 2,700 A — from 200 kW up to 50 MW — across all internationally recognised medium voltage ratings: 2.3 kV, 3.3 kV, 4.16 kV, 6 kV, 6.6 kV, 10 kV, 11 kV, 13.8 kV and 15
kV. It replaces fixed-speed direct-on-line starting with step-free,
continuously controlled acceleration.
The technology is phase-angle control of SCR (thyristor) devices.
By gradually raising motor terminal voltage from a set initial
point up to full supply voltage, the HRVS-DN lets you tune starting
current and starting torque precisely to the motor and load. The
alternative — direct-on-line starting — exposes the motor to surge
current up to six times rated current, stressing both the supply
and the switchgear, and produces a very high peak torque that loads
the motor, the driven machine, V-belts and gearing. Conventional
step-reduction methods such as reactors and autotransformers only
reduce voltage in discrete steps; the HRVS-DN ramps it
continuously. Soft stopping is a standard feature, which is decisive in pumping applications to prevent water hammer
and on conveyors where an abrupt stop can damage the load.
The unit is built as a complete engineered assembly, not a bare
controller. The standard package is supplied ready-to-connect in a NEMA 12 enclosure (NEMA 3R, 4 and 4X/IP67 available) and includes the digital soft starter with segregated high-voltage and low-voltage
compartments, a disconnect switch (load break / fault make, with fuses), line and bypass vacuum contactors, low voltage controls and Modbus RS485 communication as standard, with Profibus and DeviceNet optional. The advanced
digital firing system links the low voltage control to the high
voltage section through fibre optics, the HV compartment is fully segregated from the LV compartment for safe operation, and individual phase modules can be replaced individually to minimise downtime. Chassis-type OEM kits are available to
qualified integrators for building the unit into custom enclosures
or switchgear.
Frequently Asked Questions
Q1. Can the HRVS-DN start a heavy duty or high-inertia load that
will not start direct-on-line?
Yes — but certain data is needed to calculate the minimum starting
conditions, so technical support involvement is required. In
practice this means supplying the motor nameplate data, the
torque-versus-speed load curve and the load inertia, so the initial
voltage, current limit and ramp times can be set correctly.
Q2. Can it be connected to the medium voltage bus without a load
break disconnect switch?
Yes. The HRVS-DN can be supplied without a load break switch, using
inline and bypass contactors only. A fused load-break disconnect switch at the medium voltage feeder
is sufficient. The fuses serve only as cable protection and
protection against catastrophic failure. Motor protection is
usually included in the circuit breaker, or the soft starter can be
equipped with a comprehensive motor protection relay (MPS3000 or
equivalent). If an existing circuit breaker is used, it can remain
closed or switch in the no-current condition — except under fault
conditions.
Q3. Can the HRVS-DN start synchronous motors or slip-ring motors?
Yes for both. A non-excited synchronous motor behaves essentially
the same as a squirrel cage induction motor: once it reaches rated
speed in the non-excited condition (equivalent to rated slip in
induction motor operation), the excitation system — which Solcon
can also supply — is switched in and the motor pulls into
synchronised mode. Slip-ring motors can also be used, unless the slip-ring motor was originally specified because of
especially high starting torque requirements — in that case a soft starter cannot be used.
Q4. Is an explosion-proof version available?
Yes, with (EEx-D)[ia]I certification. Solcon states that it is the only MV soft starter manufacturer in the world to offer this
certification. This is relevant for hazardous-area installations where the
starter must be installed within the classified zone rather than in
a remote safe area.
Q5. Can one HRVS-DN start more than one motor?
Yes. Two parameter sets can be programmed via the Dual Adjustment function, so two different motor types can be started. In practice
there may be little difference in actual motor output. Several
identical motors can be started from one unit, but because of the
higher thermal load a larger soft starter (always equipped with a fan) must be used. Alternatively, one or several additional cabinets with vacuum
contactors can be supplied for sequential starting of multiple
motors.
Q6. Is it available for outdoor installation, and does it meet
industry-specific standards?
Yes. Outdoor and harsh-environment enclosures are available: NEMA 3R, NEMA 4 and NEMA 4X (IP67). On standards, the HRVS-DN is designed and built to meet IEC, EN, DIN VDE, NEMA, UL/CUL and IEEE, with DNV and ABS or similar class approvals on request. It can also operate at high altitudes (for example 4,000 m above
sea level) provided nominal voltage and current are reduced per the
derating table and the starting frequency may need to be reduced.
If your supply voltage is an intermediate value not listed, select
the next higher voltage class and specify the actual supply voltage
when ordering.
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