I'm experiencing issues with an older DC Drive, specifically a BBC Veritron 10 hp model that powers a 10 hp motor via a 5:1 gearbox, which drives a flat belt conveyor. The drive seems to lack power when the load on the belt increases, causing it to stop unexpectedly. After a few minutes, it trips the overload protection, which I suspect is linked to the armature leads (there's only one). I have already replaced the motor, inspected the gearbox, and examined the bearings on the conveyor belt, but I haven't encountered any faults on the drive—at least none that are visible. Given the drive's age (around 30 years), could it simply be failing? I'm considering acquiring a replacement in hopes of resolving the issue, but I'm still uncertain whether the drive is the root of the problem. Notably, the motor remains cool, and when the gearbox is disengaged from the belt, it runs smoothly with no load. Any suggestions or insights would be greatly appreciated. Thank you!
If your motor features a separate field supply, it's essential to ensure that it's functioning correctly and delivering the appropriate voltage. Whether you're working with a new motor or a pre-owned spare, keep in mind that if you're using a second-hand motor equipped with a Permanent Magnet (PM) field, the magnetism may have diminished after three decades. Additionally, consider inspecting the bearings on the conveyor, as they could also be contributing to performance issues. In many cases, replacing the motor and bearings might be the most effective solution for optimal operation.
Without using a DC ammeter to check the armature current, it's nearly impossible to diagnose the system's condition. The armature current plays a crucial role, as it is directly tied to the torque output. It's possible that the drive is providing maximum current. Additionally, it's essential to measure both the field current and voltage to ensure proper excitation. A stronger field, represented by Watts per Ampere-Turns, results in a higher torque constant (Kt in FtLb/Amp) and a lower back EMF constant (Ke in RPM/V). Think of it like changing the gearing in a vehicle. If the field is partially shorted and powered by a current-regulated supply, you might observe low field voltage but correct current levels. On the other hand, if you’re using a voltage-regulated field supply, the voltage will appear normal, but the current may be excessively high. In short, troubleshooting a DC drive effectively requires the use of a DC ammeter for accurate diagnostics.
It appears that you've encountered an issue with the field power supply. Without a functional field supply, the motor cannot generate torque, leading to excessive current in the armature and triggering overload protection. To resolve this, first, check the field supply. If it’s absent, consider replacing the entire system with a reliable Variable Frequency Drive (VFD). Upgrading to an AC VFD is advantageous compared to a DC setup, as it offers improved performance and efficiency.
GaryS remarked: "An AC VFD (Variable Frequency Drive) is always superior to a DC counterpart." Click here to read more... Oh no, you've stirred up quite a discussion now!
With an AC drive system, I can accomplish everything possible with a DC drive system—and much more. I'm always open to discussing this topic further. There are numerous advantages of using AC drives compared to DC drives, making them a superior choice in many applications.
✅ Work Order Management
✅ Asset Tracking
✅ Preventive Maintenance
✅ Inspection Report
We have received your information. We will share Schedule Demo details on your Mail Id.
Join hundreds of satisfied customers who have transformed their maintenance processes.
Sign up today and start optimizing your workflow.