Emergency Generators for Pump Stations 1

[mflam]

I want to put hard wired emergency generators at wastewater several wastewater pump stations.
The problem is that the industrial grade generators are too big.
For example,
a seven lot subdivision, pump station has two 5 hp pumps and they never both run at the same time. The actual KW that I need to power is about 4 but the smallest industrial generator is around 25 KW.

Has anyone had any experience with putting an appropriately sized residential generator (12-15 KW range) at wastewater pump stations?

What's the down side?

 

[bimr]

There is no downside to installing standby power. You just need to make sure that it lockable and bolted down.

I have used Generac residential units for very small systems. If possible, power it with natural gas so you do not have to worry about refueling.

 

[racookpe1978]

Good point. There is a lot to be said for "too big to look like you can steal" as well.

 

[eea]

Please check your pumps' startup amperage draw to insure your proposed gen set can handle it. While I'd agree that having two "pump on" calls at the same time should be a rare occurrence, it is possible by the standard float set / controller configuration and from the event that knocked out grid power.

Some of the newer residential units do come with "load shedding" technology, that is if the amperage draw is greater than what the gen set can handle it'll start dropping circuits. Not sure if this just trips the breaker for a manual reset or if it tries again after a set period? This gets even more complicated because most all controllers duty cycle between the two pumps. I'd see if you could work through the load shedding and the second pump on call, elsewise just upsize the gen set for startup amperage for both pumps and sleep easy.

I personally have a home 20kW Generac that tops out at 85amps, so I appreciate the situation. However the City I work with has all CAT / Olympian diesel gen sets (varied kW ratings depending on pump needs at each station), even on a smaller cul-de-sac similar to what you've described.

Downside to a residential unit versus an industrial one is its rated life. Run some estimated life numbers and also review the continuous rated operating time of the gen set. The residential unit will have a warning for prolonged continuous use. My home's 20kW is just an air cooled 18hp lawn mower engine. Is it really rated for running a week after an ice storm? I'd rate the residential unit at 5 to 10 years of life in this installation and a diesel easily at 20+. We've had the same CAT diesel backup unit at the sewer plant since 1973! It is annually serviced and certified by the OEM. I think you'll find that in the case of upfront versus overall cost the industrial unit will prevail.

 

[chicopee]

let's see, two generators, controllers and lighting equipment. At start up, amperage will be ,I guess about 3X running amperage, so may be 20KW may not be too far fetch.