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| ats:relay [2024/05/25 12:28] – removed - external edit (Unknown date) 127.0.0.1 | ats:relay [2024/06/10 22:38] (current) – [Auto Mains Fail Transfer Switch :: Relay Logic] Alan Shea | ||
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| + | ======Auto Mains Fail Transfer Switch :: Relay Logic ==== | ||
| + | This Auto Mains Fail or Automatic Transfer Switch uses [[https:// | ||
| + | {{ : | ||
| + | One or more [[ats: | ||
| + | |||
| + | ====Motor Contactor Selection== | ||
| + | The appropriate size of motor contactors should be selected based on the load served and the genset size. The 400A frame is a good general purpose selection, but smaller or larger can substituted. Recommended source: [[https:// | ||
| + | |||
| + | * //See the discussion at [[ats: | ||
| + | \\ | ||
| + | |||
| + | ---- | ||
| + | \\ | ||
| + | <WRAP center round alert 60%> | ||
| + | \\ | ||
| + | **See warnings below** | ||
| + | </ | ||
| + | \\ | ||
| + | ---- | ||
| + | |||
| + | =====One-Line Diagram=== | ||
| + | {{ : | ||
| + | ===Auto Mains Fail Transfer Switch -- Selector Switch== | ||
| + | <WRAP col2> | ||
| + | One-line diagram, detailed schematic/ | ||
| + | * {{ : | ||
| + | * {{ : | ||
| + | \\ | ||
| + | //(.dsn) files can be edited with [[: | ||
| + | |||
| + | </ | ||
| + | |||
| + | ====Description of Operation=== | ||
| + | Contactors K-U [13] and K-G [14] are mechanically and electrically interlocked to ensure that only one can be closed at a time. | ||
| + | |||
| + | ===Definitions== | ||
| + | * **Utility Connected: | ||
| + | * **Generator Connected: | ||
| + | * **Load Connected: | ||
| + | * **K-G [13], K-U [14]**: Utility & Generator Power Contactors, 400 Amp 3-pole | ||
| + | * **K-PHM-U [2], K-PHM-G [10]** : Phase Monitor -- Loss of phase, phase rotation, and low voltage relay | ||
| + | * **K-VM-UA [3], K-VM-GA [9]** : Over voltage relay | ||
| + | * **K-US [4], K-GS [8]** : Time Delay (Voltage stabilization) | ||
| + | * **K-U ENABLE [5]** : Time delay to ensure utility/ | ||
| + | * **K-G STOP [6]** : Generator cool-down delay | ||
| + | * **K-G START [7]** : Generator start delay after utility power failure | ||
| + | |||
| + | ===Utility Power Failure== | ||
| + | - Starting with Utility Power being supplied to the load: Contactor K-U [13] is closed, and all timers have expired.((Time delays listed are defaults, and can be adjusted as desired.)) Timer K-G STOP [6] has expired and its contacts are closed. | ||
| + | - Power is removed from the coil for K-U [13] if: | ||
| + | - Utility power fails | ||
| + | - A phase is lost or the voltage drops below the limit set by K-PHM-U [2] | ||
| + | - Voltage goes above the limit set by K-VM-UA [3] | ||
| + | - When K-U [13] opens: | ||
| + | - Load is disconnected (Preventing damage to equipment caused by low voltage.) | ||
| + | - Removes power from timer K-G START [7], which starts its timer. | ||
| + | - If Utility/ | ||
| + | - K-U [13] will close after K-US [4] delay | ||
| + | - K-G STOP [6] will time out, potentially running the genset for up to K-G STOP [6] time delay. | ||
| + | - When timer K-G START [7] expires (30 seconds), its contacts close, which causes the selected genset to begin its autostart sequence. | ||
| + | - Once the generator is supplying power: | ||
| + | - K-PHM-G [10] qualifies all phases live, phase rotation, and minimum voltage | ||
| + | - K-VM-GA [9] qualifies maximum voltage | ||
| + | - Illuminates L-G (Blue) indicating generator power is OK. | ||
| + | - K-GS [8] begins its countdown (30 seconds). | ||
| + | - K-G [14] then closes: | ||
| + | - Supplies generator power to the load | ||
| + | - Opens the neutral connection for the coil on K-U [13], preventing K-U [13] from closing by accident. | ||
| + | - Illuminates L-KG (Blue) indicating that generator is supplying the load. | ||
| + | |||
| + | ===Utility Power Return== | ||
| + | - When Utility Power returns, it must meet the constraints: | ||
| + | - K-PHM-U [2] for phase (all phases live, correct phase rotation) and minimum voltage | ||
| + | - K-VM-UA [3] maximum voltage | ||
| + | - Indicator L-U (Green) illuminates to confirm utility grid voltage is acceptable | ||
| + | - K-US [4] begins voltage stabilization delay (10 seconds). | ||
| + | - K-U ENABLE [5] begins time delay (15 minutes), which ensures: | ||
| + | - The utility grid has time to stabilize | ||
| + | - Delays adding loads to the grid after an outage | ||
| + | - Eliminates short-cycling if the grid drops again shortly after returning | ||
| + | - Provides a minimum run-time for the generator to ensure it gets up to temperature | ||
| + | - When K-U ENABLE [5] turns on, it opens the coil for K-G [14]: | ||
| + | - Disconnects load from Generator | ||
| + | - Connects neutral of K-U [13] coil | ||
| + | - K-U [13] closes immediately | ||
| + | - Connects load to Utility Grid | ||
| + | - Disables K-G [14] by disconnecting neutral of coil | ||
| + | - Illuminates L-KU (Green), indicating Utility/ | ||
| + | - Provides power to K-G STOP [6] | ||
| + | - K-G STOP [6] begins time delay (2 minutes) for Generator cool-down (running with no load) | ||
| + | - K-G START [7] turns on, disconnecting the generator auto-start signal | ||
| + | - Genset stops | ||
| + | |||
| + | ====Bill of Materials== | ||
| + | ===116 ATS -- Automatic Transfer Switch-Contactor=== | ||
| + | |||
| + | * [[https:// | ||
| + | * [[https:// | ||
| + | * [[https:// | ||
| + | * [[https:// | ||
| + | |||
| + | < | ||
| + | |||
| + | |||
| + | {{page>: | ||
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