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18 Item(s)

FAQ

What is special about the MCI Compressor Starter? Can I use a “normal” MCI soft starter to soft start a compressor?
- Answer: Yes, a normal MCI can be used to control (soft start) a compressor. The difference is that the MCI Compressor soft starter is pre-set from factory to ensure fast and reliable start of three phase compressors.
Can the MCI soft starter be used as a switch or do I need also to install a contactor?
- Answer: The MCI can be used as a switch, therefore it is not necessary to use an additional contactor. The type of equipment that can be used for operational switching is specified in EN 60364-5. Included here are: contactors and semiconductor devices. It is also specified that not all conductors have to be connected. The conclusion is that a two-phase disconnection by semiconductors is sufficient to meet the requirements in relevant standards for operation of motor loads. Therefore there is no difference between a contactor breaking all three phases mechanically and a semiconductor motor controller like the MCI.
Why does the MCI soft starter only control 2 of the 3 phases?
- Answer: From a technical point of view, it is not necessary to control all three phases except for bigger motors where a high starting torque is important. The un-controlled phase will “follow” the other two phases and the starting current will be reduced in all three phases. The un-controlled phase current will always be approx. 15% higher than the controlled phases.
Why do the MCI 15 and MCI 25 not feature integrated by-pass of semiconductors?
- Answer: "An automatic by-pass function would require integration of mechanical relays. This would restrict the MCI application and limit the number of starts per hour. Instead the semiconductor design allows that the conductors stay in circuit also when the motor is running with nominal speed. Furthermore the heat sink design ensures that the MCI can withstand maximum load even at an ambient temperature of 40¢ªC. The maximum load is expressed in the rating index according to EN 60947-4-2: Example with MCI 25: AC-53a: 25A: 8-3:100-3000 AC-53a is the load category for asynchronous motors. 25A is the max. permissible load for the MCI 25. 8-3 means that the start profile can be 8 * 25A = 200 A for 3 seconds. A 100% load factor or 3000 operations per hour is accepted."
What does “automatic detection of missing phases” mean?
- Answer: "The MCI can detect if a motor phase (load) or supplying phase is missing. In such situations the two LEDs will flash and the MCI will not activate. It will only detect the phase failure in stand-by mode. The MCI should always be connected to a three-phase motor in order to be operated. "
Do you have a soft motor starter for 100 HP?
- Answer: MCI 50-3 I-O, the biggest soft starter in our CI-tronic™ range, is for a max. motor power of 40 HP if bypassed during steady state. For even higher rating, we recommend the Danfoss MCD soft starters from the VLT® Drives range.
I have mounted a Softstarter MCI C on my air compressor - why doesn't it work?
- Answer: For your compressor, you should use a standard MCI softstarter where you can adjust the start parameters. The MCI C compressor soft starters are specifically designed for soft starting of 3-phase compressors and have default settings.
How do I select the correct soft starter?
- Answer: First you have to keep in mind that a soft starter reduces the starting current. You must select a softstarter which supplies adequate current to ensure smooth operation of the motor or application. Please consider the number of starts per hour and the ambient temperature and also the necessary monitoring and control functions.
Do soft starters have any internal protection?
- Answer: No, they do not have any protection. You need to use a circuit breaker before the soft starter, or use fuse and contactor with thermal relay, which ensures protection againts overloads and short-circuit.
What is maximum overload current of soft starters?
- Answer: Maximum overload current for soft starters is 6xIn or 8xIn (where In is nominal current). For more details (duty ratio, number of cycles/hour, time between each start operation) please refer to overload current profile in our technical brochure.
I have a 21 kW motor application with star-delta starter, how can I change to softstarter in the cheapest way?
- Answer: We recommend the MCI 40 with inside-delta connection.
What is trip class?
- Answer: Trip class is the expression used in connection with the designation and current settings of overload relays and soft starters. The most popular are 10A and 10 trip classes. They are suitable for light/standard duty applications. Trip class corresponding to minimum overload current withstand time. For example: Class 10A = overload ratio 8 (8 times nominal current) for 1.6 seconds; Class 10 = overload ratio 8 for 3 seconds.
What is the difference between MCI xx and MCI xx C families?
- Answer: There is almost no hardware difference between the MCI xx and MCI xx C families, but the MCI xx C series has factory-fixed settings for compressor applications.
Why do we bypass the soft starter in steady state?
- Answer: Bypass is important when the soft starter is working in temperature above 40 °C – in this case you don't have to reduce load or duty cycle when the soft starter is bypassed in steady state. Moreover bypass eliminates the electromagnetic disturbances EMC during the full voltage operation.
Does the MCI-CH have some protection against phase change?
- Answer: No, MCI-CH has no phase change detection implemented.
How should I interpret MCI rating index AC-53b?
- Answer: AC-53b:6-6:30 means: Motor controller rating with bypass contactor; overload capability 6-6 - 6x nominal current for 6sec; 30 means time in seconds between each start operation.
How should I interpret MCI rating index AC-53a?
- Answer: AC-53a:6-5:100-480 means: Motor controller rating without bypass contactor; overload capability 6-5 - 6x nominal current for 5sec; duty ratio in % - 100%= continuous operation; 480 means number of cycles per hour.
What does AC-53a and AC-53b stands for and what is a difference?
- Answer: There are two basic utilization categories for AC semiconductor motor controllers (MCI xx): AC-53a and AC -53b. AC-53a describes operational capabilities of controlling squirrel cage motors by semiconductor controller (MCI) AC -53b describes operational capabilities of controlling squirrel cage motors by semiconductor controller (MCI) bypassed during running. Note: The means of bypassing controller may be integral with the starter or installed separately