Voltage drop for high rise building.

[binwork91]

For high riser building, how can you solve the voltage drop issue?
If you using transformer step up and step down, the transformer also cause voltage drop.
Without transformer, hundreds feet feeder cause big voltage drop as well.
What will be the solution?

 

[rlundsrud]

Correctly sizing the conductors for the drop should work.

 

[tortuga]

Start with a larger service voltage. 600Y/347?

 

[KevinKos]

Addressing the voltage drop issue in high-rise buildings without relying on transformers can be challenging. Here are some solutions:

1. Increase Conductor Size​

Using larger conductors can significantly reduce voltage drop. By increasing the cross-sectional area of the conductors, the resistance decreases, which in turn reduces the voltage drop over long distances.

2. Utilize Higher Voltage Distribution Systems​

Higher voltage systems inherently experience less voltage drop over the same distance compared to lower voltage systems. Implementing a higher voltage distribution system within the building can help mitigate voltage drop. For example, using 480V instead of 208V for distribution can be effective.

3. Distributed Electrical Rooms​

Distributing electrical rooms or panels at different levels of the building can reduce the length of the feeder runs. This minimizes the distance the electrical current has to travel, thus reducing the voltage drop.

4. Voltage Drop Calculations and Monitoring​

Regularly calculate and monitor voltage drop across different parts of the system. Ensure that the design adheres to the NEC's recommendations for maximum allowable voltage drop. The NEC recommends a maximum voltage drop of 3% for branch circuits and 5% for feeders.

5. Active Voltage Regulation​

Implement active voltage regulation devices such as voltage regulators or automatic voltage stabilizers within the building. These devices can adjust the voltage to compensate for drops and ensure a stable supply.

6. Power Factor Correction​

Improving the power factor can reduce the effective current in the system, which can help in reducing voltage drop. Installing power factor correction capacitors at strategic points in the system can improve the power factor.

7. Dedicated High-Current Paths​

For high-current loads, consider dedicated high-current paths with minimal voltage drop. This could involve using busbars or other high-capacity conductors designed to carry large currents with minimal resistance.

Each of these methods can be tailored to the specific needs of the building and the electrical load profile. Implementing a combination of these strategies often yields the best results in mitigating voltage drop issues in high-rise buildings.

 

[zbang]

Depends on how high.
Depends on the per-floor loads (dwelling, office, data center!)
Depends on what's available from the PoCo.

I've seen 12 story buildings supplied with 11kv and others of roughly the same size with 480v, and they all had transformers on each floor.

 

[binwork91]

If feeder run is too long, I think step up voltage at the beginning and step down voltage at the end won't be a good idea, since each transformer will cause voltage drop as well. 3% voltage drop is hard to get if there are two transformer. For sure the impedance of transformer is a key factor.

 

[ron]

If feeder run is too long, I think step up voltage at the beginning and step down voltage at the end won't be a good idea, since each transformer will cause voltage drop as well. 3% voltage drop is hard to get if there are two transformer. For sure the impedance of transformer is a key factor.

When this method is done, the 2nd transformer has its taps changed to account for voltage drop

 

[winnie]

The step-up/step-down approach can be made to work, however the 'voltage drop' in the transformer must be considered carefully.

Keep in mind that for most transformers the bulk of the impedance is inductive. This means that the 'voltage drop' in the transformer is a vector which is nearly perpendicular to the applied load _if_ the applied load is resistive. So two 5% impedance transformers in series will generally result in quite a bit less than 10% voltage drop at the load.

Ideally the power company supplies power are more than the final utilization voltage, and then only a single transformer is used to get down to the customer utilization voltage on each floor of the high-rise.

-Jonathan

 

[binwork91]

When this method is done, the 2nd transformer has its taps changed to account for voltage drop

if use tap to change the voltage, will it cause high voltage when the load is low? It might damage the equipment.

 

[electrofelon]

If feeder run is too long, I think step up voltage at the beginning and step down voltage at the end won't be a good idea, since each transformer will cause voltage drop as well. 3% voltage drop is hard to get if there are two transformer.

Exactly, and this drives me crazy. Seems like everyone and their brother compares a no transformer scheme to a transformer scheme and uses say 3% as the target with no transformers, and completely ignores voltage drops and losses in the transformers, which is about as Fair as a Russian or Iranian election.

 

[binwork91]

6. Power Factor Correction​

Improving the power factor can reduce the effective current in the system, which can help in reducing voltage drop. Installing power factor correction capacitors at strategic points in the system can improve the power factor.

Is it common to use capacitor bank to correct the power factor when there is voltage drop issue?
I have face a project with high impedance transformer (7%). Transformer manufacture recommend to use power factor correction and capacitors instead reduce the impedance of transformer. They said "Going down with impedance may not have big effect, but it will increase transformer cost."
I know it cost more, but it helps with low impedance transformer.
Should i consider power factor correction instead of low impedance transformer?