Following on our generator maintenance tips in the Aug. 1 issue, consulting engineer Charles “Buc” Fitch, P.E., offers 10 important points to keep in mind when planning to purchase a new one. This is not a comprehensive primer but rather a list of factors to consider or help you ask intelligent questions of your generator supplier.
Point (1) is to choose the proper power sizing for the task and character of the load. Then (2) determine the best choice for fuel. Local ordinances may restrict certain types.
Also (3) consider the operating noise level, which in some instances may be regulated by local ordinance. When it comes to the engine muffler system, Buc says, “more quiet” tends to mean “more cost.”
Consider ease of access (4) for maintenance. Others will probably install and maintain your system, but you don’t want to create a situation where they need you to remove a wall to change the oil or rearrange cars in the parking lot to access the equipment.
For your operating budget (5), determine the true cost of operation. The price is what you pay for something but your true cost is the total you pay to obtain and use it. This includes the generator’s price along with cost of installation, a maintenance contract, fuel, required fencing, pilasters, etc. For comparing models and scenarios, you can divide total cost by the anticipated number of life hours.
It’s also important (6) to figure in the cost of alleviating damage or vandalism once the generator is installed. Consider how to protect the unit from damage and vandalism as well as its overall hygiene. Since every generator purchase is a capital investment, prudence dictates that you have the proper fencing, locked cabinets and maybe a security camera.
Fire safety (7) is another consideration. All power-generating systems have fire safety issues. Each fossil fuel has its own risk level, and depending on that fuel, you may be required to provide containment, suppression or detection systems to match the risk.
Another consideration (8) is run-time cycling. This depends on the character, frequency and duration of your outages. The choice of fuel and engine speed will be a function of these factors.
Explore available options (9). As when buying a new car, you’ll be presented with a list of optional choices, and many can be useful. This may include remote monitoring and control through the internet; a fuel level sensor that can summon the fuel company; an excessive run indicator; an engine hours meter; and an alarm to warn of failure to start on exercise. It probably will be cheaper and easier to buy these with the unit than adding them later.
Finally, consider what your needs might be in the future (10). Within reason, look somewhat ahead. For example, the possible future addition of an N+1 FM backup transmitter on your studio STL tower might dictate the need for an extra 10 kW of power. Ditto at the transmitter site, where a few extra kW of capacity might be needed for future tower clients.
This is a big project so don’t go it alone. Reach out to your peers for their experiences and recommendations. A few phone calls or chat at an SBE meeting can often save you from serious errors or omissions. Part of our job description as radio engineering managers is to make not just good decisions, but the BEST decisions.
Any tips of your own to share about choosing and installing a generator? Email me at [email protected].
And in closing, Buc adds: “Don’t forget to mail in the warranty card.”
Not all capacitors are equal
Longtime Workbench contributor Paul Sagi reminds us that when we are repairing gear, we should use capacitors with low ESR, or equivalent series resistance. A lower ESR results in higher deliverable current levels along with a lower voltage drop, which improves the circuit performance.
They are worth a slightly higher price, especially when used in digital circuits or switched-mode power supplies. Paul has repaired a SMPS from a server of a major computer manufacturer that “blew up” because ordinary capacitors had been substituted for the main filter capacitors, after the rectifier bridge. He suspects that an inexperienced engineer thought the ripple would be only 50 or 60 Hz, not realizing that a major ripple component in an SMPS would be the 100 kHz switching frequency. The main filter caps overheated, shorted and ruptured, blowing the input fuse.
Fortunately the fix was simple: Clean out the cap innards gunk, install low-ESR capacitors and replace the fuse. The EMI filter and rectifier bridge tested fine — those components had been saved by the fuse.
Workbench submissions are encouraged and qualify for SBE recertification credit. Email [email protected].
