Thermostat device with line under frequency detection and load shedding capability

• US 7,595,567 B1
• Filed: 06/08/2007
• Issued: 09/29/2009
• Est. Priority Date: 07/08/2003
• Status: Active Grant

• Current Assignee: Eaton Intelligent Power Limited (Eaton Corporation PLC.)
• Original Assignee: Cannon Technologies Co.
• Inventors: Ockert, William R., Allmaras, Kevin, Cannon, Joel R., Cox, Robert
• Primary Examiner(s): DeBeradinis; Robert L.
• Application Number:
  US11/811,144
• Time in Patent Office: 844 Days
• Field of Search: 307/129, 307/29
• US Class Current: 307/29
• CPC Class Codes: H02J 2310/52 The controlling of the operation of the load not being the total disconnection of the load, i.e. entering a degraded mode or in current limitation
• CPC Class Codes: H02J 2310/54 according to a pre-established time schedule
• CPC Class Codes: H02J 2310/60 Limiting power consumption in the network or in one section of the network, e.g. load shedding or peak shaving
• CPC Class Codes: H02J 3/14 by switching loads on to, or off from, network, e.g. progressively balanced loading
• CPC Class Codes: Y02B 70/3225 Demand response systems, e.g. load shedding, peak shaving
• CPC Class Codes: Y04S 20/222 Demand response systems, e.g. load shedding, peak shaving

Abstract

An under frequency protection thermostat-type device includes a thermostat-type housing, a transformer, a line under frequency (LUF) detection and measurement module, a microcontroller, and a load switch. The transformer is adapted to be electrically connected to a primary voltage source having a predefined frequency level and disposed within the housing. The LUF detection and measurement module is electrically connected to the transformer and adapted to detect a line under frequency condition from a signal received from the transformer. The microcontroller is connected to the LUF detection and measurement module and is adapted to send a command to disengage and engage an electrical load as a function of a measured frequency of the voltage source over a predefined period of time. The measured frequency is compared to a predefined frequency threshold. The load switch is connected to the microcontroller and is adapted to respond to a command from the microcontroller to disengage and engage an electrical load from the voltage source.

Claims

1. An under frequency protection thermostat-type device comprising:

a thermostat-type housing;

a transformer adapted to be electrically connected to a primary voltage source having a predefined frequency level and disposed within said housing;

a line under frequency (LUF) detection and measurement module electrically connected to the transformer and adapted to detect a line under frequency condition from a signal received from the transformer;

a microcontroller connected to the LUF detection and measurement module and adapted to send a command to disengage and engage an electrical load as a function of a measured frequency of the voltage source over a predefined period of time, wherein the measured frequency is compared to a predefined frequency threshold; and

a load switch connected to the microcontroller adapted to respond to a command from the microcontroller to disengage and engage an electrical load from the voltage source.

2. An under frequency protection thermostat-type device comprising:

a thermostat-type housing;

a transformer disposed within said housing;

a line under frequency (LUF) detection and measurement module electrically connected to the transformer and adapted to detect a line under frequency condition from a signal received from the transformer;

a microcontroller connected to the LUF detection and measurement module and adapted to send a command to disengage and engage an electrical load as a function of a measured frequency of the voltage source over a predefined period of time, wherein the measured frequency is compared to a predefined frequency threshold.

3. The device according to claim 2, wherein the transformer is adapted to be electrically connected to a primary voltage source having a predefined frequency level.

4. The device according to claim 2, further comprising a load connected to the microcontroller and adapted to respond to a command from the microcontroller to disengage and engage an electrical load from the voltage source.

5. The device of claim 2, wherein the LUF detection module is adapted to determine the line frequency status of each power line cycle by counting ticks on an interval timer between two successive zero-crossing falling edges of the power line, thereby generating the measured frequency of the voltage source.

6. The device of claim 2, wherein the microcontroller sends a command to disengage the load when the measured frequency over the predefined period of time is below the frequency threshold and sends a command to engage the load when the measured frequency is above the frequency threshold.