The Uninterruptible Power Supply (UPS) system protects sensitive equipment against power interruptions. Within the UPS, the bypass switch plays a crucial role in maintaining a consistent electricity supply to critical devices. In this blog, we will explore the detailed functions of a UPS bypass switch, as well as the significance of inverter bypass mode in ensuring reliable power.
What does a Bypass Switch in a UPS System Do?
The UPS system, made up of a unit and backup battery, is essential for safeguarding against power outages, with its bypass switch ensuring continuity during maintenance. An external maintenance bypass switch permits the seamless transfer of the critical load from the UPS output directly to the main power source. This allows the UPS system to be entirely disconnected, enabling specialized engineers to perform comprehensive servicing.
In the absence of an emergency maintenance bypass switch, the only non-intrusive maintenance method involves powering down the critical loads. Given the associated risks with this method, the UPS bypass switch becomes a necessity in various scenarios to circumvent the shutting down of vital power systems.
What is Normal Mode and Bypass Mode in Inverter?
When the inverter operates in normal mode, it provides output through its circuit board. If damaged, the output stops, causing the inverter’s normal mode to malfunction.
The inverter bypass mode holds critical importance in any inverter or UPS. If your inverter stops operating and producing output, you can still power your load by setting the inverter switch in bypass mode for emergency purposes.
How does a Static Bypass in UPS Inverter Work?
A UPS Inverter, connected to a battery bank, draws direct current (DC) and converts it to consistent alternating current (AC). If the UPS inverter fails, the static bypass switch detects the voltage drop and quickly switches to the grid’s AC power, ensuring uninterrupted power to the connected loads. This allows the UPS inverter to be serviced or replaced without causing power disruptions.
Also See: How to Ground Solar Inverter
Why does an Inverter Need to have a Bypass Mode?
Grid-tied inverters feature a static bypass switch, ensuring AC loads continue on grid power during inverter or battery malfunctions. In contrast to off-grid systems, which rely entirely on battery banks charged by solar panels, wind turbines, or backup generators, grid-tied systems use the power grid as backup. When the battery bank depletes, or the inverter malfunctions, leaving no alternative power for AC loads, the inverter switches to bypass mode. This mode routes grid AC directly to the distribution panel and AC loads, permitting the inverter’s repair or replacement and allowing the battery to recharge.
Additionally, check out the 8 Reasons Inverter Keeps Switching On and Off
What is the Difference Between Static Bypass and Maintenance Bypass in UPS?
There are two primary bypass switches: static bypass and external maintenance bypass. Static bypass automatically rectifies faults, and the external maintenance bypass is designed for planned manual interventions. External maintenance bypass also comes with an auto-transfer feature that can serve as a viable alternative.
Take a look at this table summarizing static bypass vs maintenance bypass.
|Static Bypass||Maintenance Bypass|
|It acts as an internal safety mechanism ensuring uninterrupted power.||Typically positioned externally to the UPS, it maintains power during repairs.|
|This switch uses two SCRs placed in a reverse parallel composition of a communication switch.||It is available in rotary or MCB formats.|
|In cases of UPS overload or internal faults, it automatically shifts the load to the main supply.||It ensures the load stays powered from the mains during UPS maintenance.|
|Lower risk due to automatic operation.||Higher risk due to manual operation.|
Therefore, it’s essential to distinguish between the static UPS bypass switch, which operates automatically, and the maintenance bypass switch, which is manually engaged during UPS Inverter servicing or replacement.
Note that due to the manual nature of this switch and associated risks, it is critical to set the system in static bypass mode before using the maintenance bypass to prevent potential damage to the UPS system.
What are the External Maintenance UPS Bypass Switch Benefits?
Incorporating an external maintenance UPS bypass switch offers the following benefits:
- Allows for the easy removal of the UPS system from the infrastructure for routine electrical testing.
- Allowing for the entire replacement, or enhancement of the UPS system without interrupting the critical load.
- Provides an easy transition between robust input and load wiring and the more flexible wires commonly associated with UPS systems.
- Ensures local disconnect at the UPS point.
Cross-Reference: Maintenance bypass installation scheme
To sum up, a UPS bypass switch serves as a safety feature in an electrical system. It swiftly transfers power to the mains during internal faults or repair works, ensuring continuous and safe power to the connected devices. To access more interesting topics, keep scrolling through our blog posts.