--- title: How the 'Over voltage' alarm works description: When the voltage of a cooler is greater than the maximum run, or start voltage, for more than 10 seconds, the SCS Controller can switch off the compressor to protect the asset and trigger an alarm to alert the site manager or staff. --- [Skip to content](https://support.aofrio.com/how-the-over-voltage-alarm-works#main-content) - [English](https://support.aofrio.com/how-the-over-voltage-alarm-works) - [Español - México](https://support.aofrio.com/es-mx/cómo-funciona-la-alarma-de-sobretensión) - [Português - Brasil](https://support.aofrio.com/pt-br/como-funciona-o-alarme-de-sobretensão) English Show submenu for translations ![](https://support.aofrio.com/hs-fs/hubfs/e7b764c0-c89a-4e26-92a2-ab6256f23c6a_medium.png?width=100&height=75&name=e7b764c0-c89a-4e26-92a2-ab6256f23c6a_medium.png) Open main navigation Close main navigation - - [English](https://support.aofrio.com/how-the-over-voltage-alarm-works) - [Español - México](https://support.aofrio.com/es-mx/cómo-funciona-la-alarma-de-sobretensión) - [Português - Brasil](https://support.aofrio.com/pt-br/como-funciona-o-alarme-de-sobretensão) English Show submenu for translations - Contact us Contact us How can we help you? - There are no suggestions because the search field is empty. 1. [Help Center](https://support.aofrio.com/?hsLang=en) 2. [IoT hardware operation & behavior](https://support.aofrio.com/iot-hardware-operation-behavior?hsLang=en) 3. [SCS Controller - Faults & Alarms](https://support.aofrio.com/iot-hardware-operation-behavior?hsLang=en#scs-controller-faults-alarms) January 24, 2025 # How the 'Over voltage' alarm works ## When the voltage of a cooler is greater than the maximum run, or start voltage, for more than 10 seconds, the SCS Controller can switch off the compressor to protect the asset and trigger an alarm to alert the site manager or staff. Review the fault logic for the "Over Voltage" alarm in the following graph: !['Over voltage' alarm](https://support.aofrio.com/hs-fs/hubfs/faultlogic_Overvoltage_ENG1.jpg?width=688&height=676&name=faultlogic_Overvoltage_ENG1.jpg) To check the present voltage for a cooler and any related alarms, or to update the parameters for 'Minimum Start Compressor Voltage' and 'Maximum Run / Start Compressor Voltage' connect to the SCS Controller with Field app. Read more about [checking power use for a cooler](https://support.aofrio.com/check-the-current-power-use-for-a-cooler?hsLang=en).   - [Support for your role](https://support.aofrio.com/support-for-your-role?hsLang=en#main-content) - [Service technician](https://support.aofrio.com/support-for-your-role?hsLang=en#service-technician) - [Hardware installer](https://support.aofrio.com/support-for-your-role?hsLang=en#hardware-installer) - [OEM buyer or engineer](https://support.aofrio.com/support-for-your-role?hsLang=en#oem-buyer-or-engineer) - [Fleet manager](https://support.aofrio.com/support-for-your-role?hsLang=en#fleet-manager) - 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