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Testing the Power Management System
With the generator in “AUTO“ position, turn the service
disconnect feeding the transfer switch contactor to the “Off”
position. The generator will start and the transfer switch will
transfer to generator power.
Press the test button on the control module of the power
management system. As the button is pressed, a relay will
energize. Each time the button is pressed, the previous relay
that was energized, will de-energize and the next relay will
energize.
Press the test button once and relay B2 will energize. Press
the test button again and B2 will de-energize and relay C1 will
energize. This will proceed until all relays have been tested or
if the test button has not been pressed for a period of
30 seconds, the test sequence will halt and the system will go
back to automatic control.
To go back to utility power, turn the service disconnect
feeding the transfer switch contactor to the “On” position.
Controls
There are no operator controls in this Power Management
System.
Operation
When the home standby system is providing power to the
transfer switch, the power management system is constantly
monitoring generator power to control loads. The power
management system monitors both incoming generator lines
and keeps the home standby system loaded to a maximum
of 85-86 percent of rated load. When the current
transformers on any line start to see current reach 85-86
percent of rated load, the power management system will
start shedding loads based on the lowest priority and work
its way to the highest priority. When current has dropped
below 85-86 percent of rated load, the power management
system will start to add loads based on the highest priority
first, followed by the second highest until the generator
reaches 85-86 percent load or all priorities are back on line.
The power management system will operate this way until
the transfer switch transfers back to utility position.
The power management system waits 5 seconds between
adding or shedding each load to permit the system to
stabilize. When a relay is opened, the relay will stay opened
for a minimum of 5 minutes or until the load can be added
without putting the generator over 85-86 percent of rated
load. If a large load demand is seen, the power management
system will shed all loads in less than 1.5 seconds to
prevent the generator from overloading. Once the demand
has stabilized, the power management system will start with
the highest priority, wait 5 seconds and then add the next
priority. The unit will continue to do this until all loads are
added or 85-86 percent of rated load is reached.
When the generator is powering loads, the A/C relays are
open. When one or both of the relays sense 24VAC from the
thermostat(s), the controller will shed loads B1-D2, and then
will allow only one A/C relay to close. A1 has priority over
A2. A2 can close when the signal for A1 has expired. When
the A/C’s are being called to run, all loads are to be shed
before the A/C unit can be added. Should A/C 1 call while
A/C 2 is running, A/C 2 shall open, all relays would open and
then A/C 1 can close. When the A/C relays open, they are to
be locked out for a minimum of 5 minutes or until they
receive a call to start the A/C.
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