Power requirements for various mission-critical facilities and data centres are growing at a rapid pace. While most specific needs of the power distribution system are based on the type of critical activities it supports and what its future expansion will be, most of them are reliant on UPS power. When you have these large-scale UPS, they need to have the right kind of grounding. Read on below to learn more about the importance of grounding in large-scale UPS systems.
Why grounding is important
These installations are generally designed with specialised N+ 1 module. The system will have the number of modules required to support the load requirements, and there is one more module for redundancy. These have the needed static-switch bypass for transferring power in case the UPS modules fail.
However, if any problem arises with these modules, the critical load gets transferred to the static-switch bypass to the UPS modules. A solid ground needs to be established in order for that transfer to take place. Generally, the grounding wire is placed along with the phase conductors; these extend to the static switch bypass to the service substation.
It is crucial that the grounding is connected properly at the point where the static bypass cabinet; the other important aspect is that zero potential needs to be maintained at the ground to neutral bond at the point where the static bypass is, as well as at the double-ended station. If these things aren’t in place, the Uninterrupted Power Supply system may just fail to get transferred to static bypass.
Some aspects to keep in view
- Most manufactures of these systems recommend the grounding conductor and the neutral are run from the UPS modules’ isolation transformers to the static-switch bypass; they are connected to the respective bus at this point.
- It is important that the ground and neutral be bonded
- A ground will need to be run from the ground and neutral bond of the double-ended substations up to the neutral ground bond located at the static switch.
- Since there isn’t any transformer positioned at the static switch to help in establishing the separately derived system, a common electrical point will be established between the static-switch bypass and the double-ended substation. However, this particular configuration can potentially create load continuity problems.
The primary reason why most data centre systems go off-line is human error and this can result in ground fault problems. It can be very difficult to predict and control grounding faults and they can cause extensive damage to large-scale UPS systems.
These systems have output isolation transformers; however, their static-switch bypass doesn’t. In case any ground fault surfaces at a point that is downstream from the UPS system, but is located upstream from the connected power distribution unit, that fault can easily get transferred back to the source (the double-ended station), and the entire system might lose power.
There are different solutions that can help mitigate all these potential impedance and ground faults such as:
- Installation of a transformer at the static switch input – This transformer can be large and expensive to install.
- Implementing high-resistance grounding – This particular solution isn’t very easy to implement. The job is quite dangerous and highly-skilled personnel are required to handle the task.
When it comes to getting ground installed for large-scale UPS systems, it’s important that skilled and experienced design engineers coordinate with you to establish the needed design parameters based on the reliability required for the mission-critical facilities.
If you want to know more about our power products and services, don’t hesitate to contact us at KaRaTec Power Supply Pty. You can give us a call at 612 9808 1127. You can also fill in this contact us form.
Thanks for reading,
Karatec Power Supply Pty
612 9808 1127