Philippine Electrical Code Common Violations – Conductor Box Fill
This is a series of articles where we shall be discussion the common violation on the Philippine Electrical Code. It is the assumption of this series of article that the Electrical installer are duly licensed by the Professional Regulations Commission, plans are checked, signed and sealed by a registered Professional Electrical Engineer, and all permits has been acquired prior...
Posted in Design on October 23rd, 2024
Selection of Variable Frequency Drives – Examples
The equations for calculating the power requirement for VFD has been discussed in Selection of Variable Frequency Drives.
Using the equation below, we will provide some examples on selecting a VFD for a specific motor.
Note:These motors are used for electric submersible pumps hence the voltages are different from the usual motor ratings.
[pmath]P_IN = {sqrt{3}*V_motor*I_motor*PF_motor}/{{eta_VFD}*{eta_motor}}[/pmath]
1. For the 150HP motor...
Posted in Design on October 22nd, 2024
Selection of Variable Frequency Drives
The size of a variable frequency drive (VFD) should be based on motor voltage and current and not on the torque or power rating. The voltage and full load current information can be taken from motor nameplate or datasheet.
[caption id="attachment_18665" align="aligncenter" width="640"] Induction Electric Motor Nameplate[/caption]
While the motor can be rated...
Posted in Design on October 17th, 2024
Power Factor Correction and Harmonic Resonance: A Risky Combination
Capacitors are intended to solve problems, but if not properly specified, they can also create new ones.
Industrial and commercial customers are always examining their monthly electrical usage for cost-saving opportunities. Installing power factor correction capacitors can help reduce penalties imposed by utilities, often leading to a quick return on investment. In locations like hospitals and paper mills, the payback...
Posted in Design on October 16th, 2024
Variable Frequency Drive Cable Length Resonance Frequency
This is a continuation of the article Effect of Cable length on Variable Frequency Drive.