|
|
|
|
|
|
|
|
|
|
|
| |
| Case
Study |
| |
| Safer and Faster Portable Generator to Lift Station Connections. |
A Wisconsin wastewater treatment
plant is saving time with a combination plug/receptacle and disconnect
switch that makes generator connections
safe, fast and easy at lift stations around town. Safety concerns led
the Watertown, WI wastewater utility to equip its portable emergency
generators and remote lift stations with Decontactors. The Meltric Decontactor™ Series
switch-rated plugs and receptacles allow workers to safely make and break
electrical connections, even under full load.
|
The city is underlain by 105 miles of sewers that collect wastewater from a 12
square mile area. The collection system also includes 18 remote lift stations.
The lift stations, located around the city, use submersible pumps to elevate
the wastewater in the sewer lines and facilitate gravity flow to the treatment
plant. Typically, they are located below ground level with a control panel
above ground. Assistant Water Systems Manager-Wastewater Kevin L. Freber
says the total capacity of the pumps is 27 million gallons per day, although
flow generally averages between three and three-and-a-half mgd.
|
|
While some lift stations are equipped with stationary generators to provide emergency
power, a power failure may make it necessary to bring the department’s
portable generators to the other lift stations and connect them to power
the pumps until service is restored. Previously, these stations were equipped
with conventional pin and sleeve connectors. However, they could not be locked
easily to prevent tampering or injury to children or vandals who might try
to remove
the plug. Freber says, “The generators deliver 100 amp service, and with
the plugs we had before, there was no way of locking the two parts together.
Any kid could walk up and pull it apart.”
Freber points out that the Decontactors are easy to lock to prevent tampering
and also are safe when they are separated. He states, “You have to twist
it to open it, and even if someone could get it apart, they never could get at
the live contacts.” This is due to their dead-front construction and enclosed
arc chambers. Easily accessible contacts on the previous connectors had the potential
to expose workers or others to live power, so switching to Meltric’s Decontactors
also helped the utility to simplify compliance with NFPA 70E arc flash requirements.
Arc flash can be a concern when it becomes necessary to switch power connections,
but the city’s lift stations that use mobile generators for emergency power
are constructed to minimize or eliminate this risk. Freber says that wiring typically
comes up from the pump into the bottom section of the control panel, which is
constructed so that the related starters and other electronics are segregated
in a sealed area. He explains, “Because of the new arc flash laws, we have
them separated so our technicians can open the outside panel without danger from
arc flash. There is also a walking beam inside, so when we switch from city power
to emergency power, the power can’t back feed. Using the Decontactor to
connect to the generator with this arrangement we can switch safely from city
to emergency power.” Now, it takes only minutes to connect a generator
and begin pumping. The ability to connect or disconnect quickly and safely makes
it easier to move generators around to various lift stations for monthly test
runs or if necessary during a prolonged or widespread power outage. |
|
|
|
|
|