Peterson Power Systems, Inc. is your authorized source for Cat distributed generation and standby power equipment. Distributed generation is power generated on-site. This eliminates inefficiencies and also has the ability to lower costs, since energy does not need to be moved across distances.
Peterson Power System offers Caterpillar's complete line of marine propulsion engines and marine generator sets that are suited for powering pleasure craft and commercial vessels. All our products offer maximum reliability with minimum operating costs for any application and vessel size.
Cogeneration is a cost-efficient means of generating both electricity and thermal energy from the same fuel source.
Peterson Power Systems supplies and fully supports complete power solution packages to meet diverse emergency electric power needs when and where they matter most.
Peterson Power Systems provides electric power generators for use in many applications, including prime power for remotely located commercial businesses where there is no access to electric power.
by Brett Greene
Sales Representative, Peterson Power Systems
(510) 618-5536 | (925) 457-5135 cell | email@example.com
The best way to select a transfer switch is to understand the types of loads connected to the standby system. Consider the characteristics of the connected load, and loads that may be connected in the future.
Here are common switch types, along with their advantages and disadvantages:
DOUBLE-THROW TRANSFER SWITCHES
This family of transfer switches provides fast load transfer with “break-before-make” action. In their standard form, they assure that the utility and the gen set are never connected simultaneously.
However, double-throw transfer switches should not be used with larger (20-hp and up) motors, compressors and transformers. Voltage in motor devices decays at much longer rates than other loads because the motor continues to rotate and the magnetic flux causes the motor to act like a generator. They will likely be out of phase if power is reconnected too quickly. Out-of-phase start-ups will trip circuit breakers or needlessly stress load and/or generator windings.
TIME-DELAY NEUTRAL TRANSFER SWITCHES
Circuits serving motors or transformers should be transferred to standby power with time-delay neutral (TDN) transfer switches, which allow flux voltages to decay before these devices are brought back on line.
TDN switch design is simple and reliable. When specifying TDN switches, select units with an adjustable time delay so it can be best set for the application.
Since most facilities with emergency power have HVAC compressors or motors, a TDN transfer switch can meet the needs of lighting and motor circuits.
IN-PHASE MONITORING SWITCHES
In-phase monitoring (IPM) transfer switches (usually an open transition switch) monitor the phase difference between the load and oncoming source. It is a more expensive transfer switch, since it anticipates the best time to trigger the transfer, or prevent it from happening if the desired power source remains out of phase with the load.
A speed (frequency) difference larger than 0.4 Hz may occur with gen sets equipped with a droop-type governor which may prolong the out of phase condition and prevent a quick transfer to the desired source. In this case, an isochronous engine governor with synchronization should be specified with the IPM to secure a quick transfer.
CLOSED TRANSITION SWITCHING
Another higher-cost option to consider is a “make-before-break” closed transition switch. It momentarily parallels the two power sources before transfer. Complex safeguards must be added to guarantee that “in-parallel” time be no longer than 100 milliseconds. These systems increase engineering costs because utilities require extensive documentation to assure grid safety. It also increases customer liability.
The owner usually has one consideration — low cost. However, the overriding goal should be a reliable system with reasonable installation and operating costs over the system life.
Before specifying a double-throw switch, be sure that motors and compressors will not be added to the gen set circuit load in the future. Upgrading to a three-position switch can cost considerably more than installing a three-position switch at initial installation.
We suggest you specify time delay neutral transfer switches with variable and immediate transfer capability. TDN switches are reliable and keep system design simple and flexible.
Assistant Chief Engineer, Nicholas Stoliar, explains how El Camino Hospital reacted to a major equipment failure. With help from Peterson Power, he had a 300 ton chiller delivered in nine hours.
Scott Posey explains Peterson capabilities as we install a 750 kW emergency standby generator set with multiple transfer switches and over sized sub-base diesel tank in Hillsboro, Oregon.
In September 2015, a state-run facility in California that serves several hundred individuals with developmental disabilities was in trouble. The facility’s main 12KV transformer failed during the night. Without the transformer functioning, the entire facility essentially shuts down, preventing it from giving adequate care to those in need. Only hours after the call came in, Peterson techs were on-site with rental equipment and support services.