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.
