MV/HV solid soft starter conducts an intelligent control of HV electrical equipment in smooth starting, parking, safety protection and monitoring. Its products include RNMZ handcart series MV/HV solid soft-starting device, RNMV-E Type MV/ HV Solid Soft Starter, RNMV-G MV/ HV Solid Soft Starter, RNMV-KY Ordinary Mine Type MV/HV Solid Soft Starter and others.
The control core of RNMV series product is microprocessor (CPU), which starts and protects the motor.
CPU controls the SCR to conduct phase angle trigger control, lowering the voltage on motor, then controls the voltage on motor and increases the motor torque of the smooth current until motor runs in full speed. The above way of starting can lower the inrush current of motor, reducing the impact on power grid and motor itself. Meanwhile, it also reduces the mechanical impacts on motor loading device, prolonging device service life and reducing motor breakdown.
Schematic Diagram of Soft Starter
Design Cabinet Type
RNMV-E/KY Type MV/ HV (3000V-10000V) Soft Starter shall be used with an inlet cabinet with a vacuum circuit breaker.
Soft Starter cabinet
The soft starting part is composed of bypass vacuum contactor, SCR high voltage components, RC absorption circuit, trigger circuit and controlling device.
Bypass vacuum contactor – motor finishes starting, it shall close off after bypass switching. The voltage rate chosen for soft starter of 3300V is 6 KV, 6000V~6600V is 7.2KV, and 10KV is 10KV.
RC absorption network - provides instantaneous voltage to protect circuit, reduce dv/dt impulse voltage, preventing damage to SCR components.
Trigger circuit- provides strong trigger pulses up to 2A to ensure the dynamic voltage equalizing of SCR in series. The trigger circuit and SCR are with high voltage, isolated from the control panel through optical fiber and transformer.
SCR high voltage components - are composed of multiple SCR in series, the number of which shall be determined by the user's motor voltage.
1.A high voltage vacuum circuit breaker can break short circuit current under special circumstances.
2. High voltage current transformer and vacuum circuit breaker coordinate in providing motor protection.
3.The high voltage part communicates with the low voltage control part through optical fiber.
4. The inbuilt 120VAC control transformer provides the control power needed for the soft starter.
5. Bypass vacuum contactor.
6. Isolation transformer
7. Control panel
8. Silicon controlled rectifier (SCR)
This picture applies to Type-E cabinet
○ A qualified controlling system passed through the strict test of Electro Magnetic Compatibility, processes with a high anti-electromagnetic interference performance; has fully independent intellectual properties in soft starter controlling technology; is capable of providing free service for users in upgrading software control systems to ensure an advance place of its products and technology.
○ It adopts the dynamic fuzzy control concept to automatically adjust motor’s starting time and torque according to the size of load torques, realizing smooth acceleration in motor. When motor speed reaches the rated working level, the bypass contactor shall automatically pull in, which solves an unmatched problem between man-made starting curve and load torque curve. Also known as a unique feature in MV/HV solid soft starter cabinet of our company compared to domestic peers.
Strong load adaptability, with 3 starting control modes:
○ Voltage ramp start: The factory setting is a voltage ramp with current limiting function, which can meet most applications. The initial torque is set to the value when the motor can just drive the load, and then the voltage gradually rises smoothly. Within the limited ramp time and motor starting current range, the motor can smoothly rise to full speed operation;
○ Current limit starting: When starting, the current quickly increases to the limit value until the motor runs at full speed;
○ Pulse kick start: Mainly used for heavy loads.
○ Free parking or soft parking is optional: it can be applied to different parking lots, such as eliminating the water hammer effect of the water pump, to meet special needs;
○ Text display function: LCD liquid crystal screen displays various working conditions and various languages are available, and there are text display instructions under programming and fault conditions, and the operation is intuitive and convenient;
○ System communication function: built-in communication port. RS-485 and remote terminal equipment multi-point communication (communication protocol Modbus and Porfibus optional) can directly communicate with the upper PC through this function to achieve remote control and remote signaling functions.
● Load type: Three-phased squirrel-cage AC asynchronous and synchronous motors
● AC voltage: 3kV, 3.3kV, 6kV, 6.6kV, 10kV AC-15%~+10%
● Insulation voltage: Line voltage: 3000V, 6000V, 10000V; Insulation voltage: 18000V, 25000V, 42000V
● Overload capacity: Continuity: 125% of controller nominal value; Overload: 500% 60 Seconds
● Frequency: 50Hz/60Hz±2Hz Auto choice
● Main circuit Components: (12 SCRS, 18SCRS OR 30SCRS Depends on the models)
● SCR Peak reverse voltage: 13000V~32500V(Decided by model)
● Phase sequence: RNMV is allowed to operate under any phase and sequence
● Instantaneous overvoltage protection: dv/dt Absorb network
● Cooling: Natural cooling
● Bypass: It has the bypass vacuum contactor which can directly start capacity. When the rated current is over 450A, fixed vacuum circuit breaker shall be adopted
.● Ambient Conditions: Cabinet temperature: 0℃~50℃(32℃-122℃); Base temperature 0℃-50℃, (-20℃-50℃ an option of a heater); Altitude of no more than 2000 meters, a relative humidity of 5%-95%; reduced capacity shall be adopted for the altitude of over 2000 meters.
● Control way: The user provides 2 or 3 line of 220 VAC or 220VDC, 1000VA.
● Auxiliary relay: C-type dry relay, 5-10A 250V, one programmable interlock relay, one bypass relay, one fault output; Relay
● Current: Two-phase timing, inverse-time limit over-current protection (limiting time quick-acting relay, limited to Type G, over-current); Two-phase negative sequence timing, inverse-time over-current protection (negative sequence limiting time quick-acting relay, limited to Type G, negative sequence over-current)
● Overload: Motor shaft lock protection & Overload alarm
● Temperature: Protection from the temperature relay (Over temperature & temperature rise)
Protection for soft-start
● Temperature: Protection for the SCR components; it shall trip when the temperature is higher than 85℃.
● Protection for over-time starting: It shall trip when the starting time is more than 120 seconds.
● Input Phase Loss: Any one loss in the three-phase power shall cause motor failure and alarm.
● Starting times in an hour: No than 6 times of starting in an hour; minimum starting interval: 5 minutes
RNMV MV/ HV Soft Starter (Stationary) Installation Way
RNMV MV/ HV Soft Starter (Stationary) Cabinet Body Schematic Diagram
Model Selection Table：
1.Bearing capacity of the soft starter: when a motor starts, the maximum starting time permitted is 15 seconds if the starting current is 5 times of the rated current one, 40 seconds for 4 times, and 70 seconds for 3 times; otherwise, please choose the product with higher power.
2.When the motor power is higher than the motor power, we shall choose the product with higher power.
3.If the motor power is within 2000kw, a differential protection box shall be added;
4.For the product with over 400A, all the bypass contactor shall adopt stationary vacuum circuit breaker instead.
5.The rated current of the soft starter shall be stated according to the rated current of user’s motor.
6. An order shall be made after negotiation for the product type of over 14000kW.