Apparatus and Method for Power and Performance Monitoring of Electric Appliances
A power monitor for an electrically powered device provides audible and/or visual alarms in the event of a power failure in a particular branch circuit. A timer records the duration of the power outage and reports the result on a built-in display. Optional performance sensors may monitor and report the condition of the electrically powered device being monitored. A representative embodiment is a monitor for a refrigerator/freezer. A temperature sensor in each of the two compartments triggers an alarm if pre-set temperature limits are exceeded. The power monitor comprises an internal, rechargeable battery which powers the device during a power outage.
1 . An electrical power monitor comprising:
a line power detector;
a power failure duration timer connected to the line power detector such that the timer starts when the line power detector detects a line power failure and stops when the line power detector detects a restoration of line power;
a display connected to the timer that displays the timer count;
a battery connected to the timer and the display such that the battery supplies power to the timer and the display during line power failures.
2 . An electrical power monitor as recited in claim 1 further comprising a line power cord having a unitized male electrical plug and a female electrical receptacle in parallel electrical connection connected to the line power detector.
3 . An electrical power monitor as recited in claim 1 wherein the line power detector comprises a timer which delays the starting of the power failure duration timer for a pre-set period of time after a power failure is detected.
4 . An electrical power monitor as recited in claim 1 wherein the line power detector comprises a timer which delays the stopping of the power failure duration timer for a per-set period of time after a restoration of line power is detected.
5 . An electrical power monitor as recited in claim 1 further comprising an audible alarm that sounds when the line power detector detects a failure of line power.
6 . An electrical power monitor as recited in claim 5 further comprising a timer that silences the audible alarm after a pre-set interval of time.
7 . An electrical power monitor as recited in claim 1 further comprising a visible alarm connected to the line power detector that is activated when the line power detector detects a line power failure.
8 . An electrical power monitor as recited in claim 7 wherein the visible alarm comprises flashing light emitting diodes.
9 . An electrical power monitor as recited in claim 8 further comprising a battery monitor that adjusts the duty cycle of the flashing light emitting diodes in response to the remaining battery capacity.
10 . An electrical power monitor as recited in claim 1 wherein the battery is a rechargeable battery and the electrical power monitor further comprises a battery charger connected to the battery.
11 . An electrical power monitor as recited in claim 1 further comprising:
at least one sensor responsive to a performance parameter of an electrical device connected in parallel with the power monitor; and,
an alarm configured to activate if the value of the performance parameter exceeds a pre-set limit.
12 . An electrical power monitor as recited in claim 10 wherein the sensor is a temperature sensor.
13 . A refrigerator/freezer monitor comprising:
a line power detector;
a power failure duration timer connected to the line power detector such that the timer starts when the line power detector detects a line power failure and stops when the line power detector detects a restoration of line power;
a display connected to the timer that displays the timer count;
a battery connected to the timer and the display such that the battery supplies power to the timer and the display during line power failures;
an alarm;
a first temperature sensor;
a second temperature sensor;
a comparator connected to the first temperature sensor and the second temperature sensor and the alarm and configured to compare a temperature reading from the first temperature sensor to a first pre-set value and to compare a temperature reading from the second temperature sensor to a second pre-set value and to activate the alarm if either temperature reading exceeds its respective, pre-set value.
14 . A refrigerator/freezer monitor as recited in claim 13 wherein the alarm is also connected to the line power detector and the alarm is activated when the line power detector detects a line power failure.
15 . A refrigerator/freezer monitor as recited in claim 13 further comprising a battery charger connected to the battery.
16 . A refrigerator/freezer monitor as recited in claim 13 further comprising a line power cord having a unitized plug comprising a male connector and a female receptacle in parallel electrical connection.
17 . A refrigerator/freezer monitor as recited in claim 13 wherein the alarm is an audible alarm.
18 . A refrigerator/freezer monitor as recited in claim 13 wherein the alarm is a visual alarm.
19 . A method for monitoring the power supplied to an electrically powered device comprising:
sampling the line power voltage supplied to an electrically powered device with a line power detector;
starting a power failure duration timer when a line power detector detects a line power failure;
stopping a power failure duration timer when a line power detector detects a restoration of line power; and,
displaying the power failure duration timer count on a display device.
20 . A method as recited in claim 19 further comprising switching a power supply connected to the timer from line power to battery power when the line power detector detects a line power failure.