Maximum Limits for Voltage Drop and Voltage Rise

Section 3.6 of AS/NZS 3000:2018 states that a maximum limit for a maximum value of voltage drops should not be more than 5% of the rated supply voltage between the source and a point in the electrical system. This is quite necessary for ensuring that appropriate levels of voltage are allowed so that electrical devices or circuits are not subjected to misoperations and equipment lifetime may be extended.

Additional Provisions for Substations

When the point of supply is a dedicated low voltage substation located on the premises, then the permissible voltage drop increases to 7%. This allowance reflects the fact that being close to the substation can mitigate some voltage drop effects, ensuring that system performance remains robust.

Stand-Alone Systems

Specific design criteria must also be met for stand-alone systems. Such systems must be configured in such a manner that the resultant combination between the output voltage from a source and a voltage drop does not lower the utilization voltage to levels below 11% of the nominal supply voltage during normal operating modes. Such careful designs are pivotal to the proper maintenance and preservation of all efficiencies in connected devices.

Determination of Limits for Voltage Drops

To aid in designing the electrical systems, the following practice guidelines can be utilized:
  • For consumers’ mains, which is considered the first part of an electrical installation, an allowance of 0.5% for voltage drop can be adopted. This helps realize maximum voltage integrity.
  • For sub-mains, there can be an acceptable value of 1.5% to 2%. This portion is branched off from the consumers mains and needs to retain voltage to serve different purposes.
  • Ultimate subgrids can tolerate a maximum voltage drop of 2.5% with other upstream supplies or at least ensure that the entire system is maintained to an acceptable level.

Voltage Increase Limits in Solar Systems

As renewable energy, such as solar power, grows in integration with electrical grids, the knowledge of what voltage rise limits are in place is important. Under the AS/NZS 4777.1:2016 standard, one must not have more than a 2% rise between the inverter and that connection point. This limiting factor ensures that the electrical system does not have high values of voltage, thereby causing safety issues and damaging components.
The AS/NZS 5033:2014 standard in DC systems determines that the maximum voltage drop should not exceed 3%. This is a sensitive limit, and it plays a significant role in achieving the efficiency of solar panels and ensuring that the energy generated is properly transmitted to the inverter with minimal losses.

In summary, it is very important to understand and follow the maximum limits of voltage drop and rise according to AS/NZS standards for the proper design and operation of low voltage electrical installations. With this, electrical systems can work safely and efficiently with proper voltage drop within the given limits, ensuring that all devices connected are working at their best.

The following regulations not only ensure conformity to legal standards but also enhance the reliability and efficiency of electrical installations. No matter whether it is working with traditional LV systems or integrating renewable energy solutions, ensuring voltage drop and rise limits is the key factor to achieving a safe and efficient electrical infrastructure.

We design and manufacture high-quality switchboards. Contact us today to discuss your requirements and get started!
Tags: