{"id":13722,"date":"2022-12-15T13:46:42","date_gmt":"2022-12-15T13:46:42","guid":{"rendered":"https:\/\/powerside.com\/?p=13722"},"modified":"2023-02-08T16:12:15","modified_gmt":"2023-02-08T16:12:15","slug":"capacitor-bank-application-for-medium-voltage-motor-starting-with-soft-starter-rvss","status":"publish","type":"post","link":"https:\/\/modomodostage.com\/_client\/PWS\/PWS101\/capacitor-bank-application-for-medium-voltage-motor-starting-with-soft-starter-rvss\/","title":{"rendered":"Capacitor Bank Application for Medium Voltage Motor Starting with Soft Starter [RVSS]"},"content":{"rendered":"\n

Product Family: PowerMVar\/SynchroMVar<\/h4>\n\n\n\n

Introduction<\/h3>\n\n\n\n

A key consideration when designing or updating an electrical system with large capacity motors is the sizing of the associated system and choice of components. Operational flexibility and redundancy needs often dictate multiple smaller units which allows for efficient operation at partial loads and reduces peak starting current. Capital cost factors favor fewer larger drives, but its starting characteristics can create high stress on the system at start-up. Soft start technologies (RVSS) and variable speed drives (VFD) help to reduce the impacts on your electrical system at start up, however, limits set by the utilities and system design can often be breached. Powerside has solutions that can significantly improve the startup behaviors of your large drives, bringing overall inrush conditions to a lower level and reducing transformer overload transients with reduced thermal overloads.<\/p>\n\n\n\n

A real application example is given below with supporting graphs to show how Powerside solutions can significantly improve system operations:<\/p>\n\n\n\n

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View results<\/a><\/div>\n<\/div>\n\n\n\n

System description<\/h4>\n\n\n\n

The primary Motor driven Compressors M1 and M2 are two 4.16kV, 2000HP units started sequentially via soft starters to rated speed before being sequentially loaded to 100%. Prior to M1 and M2 start, a 4.16kV, 2000HP Variable Frequency Drive as well as some additional Low Voltage loads are brought online. The 4.16kV bus feeds M1 and M2, while the 2000HP VFD is fed from TX-A; a 34.5kV:4.16kV transformer rated 8MVA.<\/p>\n\n\n\n

<\/p>\n\n\n\n

Main objective<\/h4>\n\n\n\n

Starting (inrush) MVA should be limited to 4MVA at utility side. This should be considered during starting M1 and M2.<\/h2>\n\n\n\n

Project objectives and imposed limits<\/h4>\n\n\n\n
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  1. Transformer TX-A is 8000\/8960 KVA and any transformer overload should be prevented.<\/li>\n\n\n\n
  2. Voltage on 4.16kV should remain in acceptable levels to prevent MV VFD unexpected shut-down<\/li>\n\n\n\n
  3. Motor thermal overload curves should be considered during acceleration.<\/li>\n<\/ol>\n\n\n\n

    Scenarios to be considered<\/h4>\n\n\n\n
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    1. M1 starts direct online (without soft starter)<\/li>\n\n\n\n
    2. M1 starts with soft starter<\/li>\n\n\n\n
    3. M1 starts with soft starter + 4MVAR capacitor bank<\/li>\n\n\n\n
    4. M1 is fully loaded and M2 starts with soft starter + 4MVAR capacitor bank<\/li>\n<\/ol>\n\n\n\n

      Inrush MVA, voltage drops at 4.16kV & utility (34.5kV) and motor starting graphs are shown for each scenario.<\/p>\n\n\n\n

      Scenarios<\/h3>\n\n\n\n

      Please note simulation starts at T:3s for better visibility.<\/h5>\n\n\n\n

      A) M1: starting in direct online mode at T-3s, M2: OFF<\/h4>\n\n\n\n
      \"Scenario