Electricity: battery or capacitor charging or discharging – Serially connected batteries or cells – Having variable number of cells or batteries in series
Reexamination Certificate
2001-02-23
2002-05-14
Toatley, Gregory (Department: 2838)
Electricity: battery or capacitor charging or discharging
Serially connected batteries or cells
Having variable number of cells or batteries in series
C320S116000
Reexamination Certificate
active
06388423
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
None
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable
BACKGROUND OF THE INVENTION:
Field of the Invention
Electric utility companies supply power which their or other generating systems produce. The power is commonly transmitted through a grid of electrical high voltage alternating (AC) three-phase power lines. Occasionally a generation, transmission or distribution facility experiences a fault in a power line, switching or operating equipment which may, for example, result in a short circuit or other equipment failure on the power line. Monitoring systems include sensing and system management equipment to isolate a problem or reroute the power transmission or distribution. These power management systems include circuit breakers or switches to effect this circuit isolation or rerouting, and the sensed fault or abnormality on a line or at a substation may cause a monitoring station to trip a circuit breaker, either rerouting or causing power interruption to a customer. Some faults, in particular high impedance faults, can occur when a power line falls onto a high impedance surface such as dry grass or an asphalt road, but the wire remains energized because the high impedance surface insulates the wire to prevent it from generating a short circuit efficient to cause the circuit to trip. Utility companies attempt to identify such faults and quickly shut down the affected line to remove the hazard of the live line on the ground.
A variety of fault sensors have been developed to detect and signal power line faults. These sensors are read in a variety of substation or central station distribution panels. The heart of the protective system operation, in the event of fault, is a battery system in such as a substation at the transmission or distribution facilities or at the central station or the generation point. Battery systems perform a critical role in these fault or emergency situations. When emergencies do occur, it is essential that the battery systems perform as designed or serious consequences result in the substations since the batteries supply the power necessary to trip or close switches and circuit breakers which effect the opening of circuits to isolate or reroute the power.
It should be understood that the heart of any transmission or distribution substation is the station battery. As one or more of the distribution system monitors, either at the generation point or some other point in the transmission system, detects abnormalities on a section of the system, corrective action is taken. This corrective action may be either manually implemented or automatically, based upon the inputs to a computerized control system. The corrective action in respect of the transmission system, is the shutting down of various components, including substations, and/or rerouting the power distribution. Since the AC power within the system supplies the process power to various of the monitors and operating equipment within the system, it stands to reason that in those situations where the system is experiencing short circuits or other faults, the system power cannot be relied upon to operate the switches and circuit breakers to either shut down or reroute power distribution. It is the station battery in these circumstances which directly provides the power necessary to reposition circuit breakers and other switches, thus should the battery system fail during a fault on the system, there may be no way of clearing the fault or short circuit leaving the system vulnerable to major burn down of the facilities and widespread blackouts. The huge fault currents occurring with hard short circuits can easily cause meltdown in transformers, distribution circuits and substation busses resulting in a major meltdowns or fires in a substation or along the distribution route, resulting in not only loss of facilities, but widespread blackouts and potential injury to personnel.
Because of the importance of good reliability of battery system, numerous maintenance programs are performed to evaluate the batteries and battery systems. Many of these are performed under static conditions such as by taking specific gravity readings, cell voltage measurements, and electrolyte level maintenance. In addition to these static tests, the voltage and the charge current to the station batteries is also monitored as an indicator of the system status. In their usual arrangements, the battery back-ups consist of a number of common lead-acid wet cells connected in series to provide the voltage and current necessary to operate the switches and circuit breakers. Such systems may include multiples of three or six cell packs each having voltages of 6 or 12 volts connected in series providing such as 120 volts and 120 to 150 ampere-hours of DC power. Such batteries exhibit some similarities to those conventionally installed in automobiles and are known to periodically exhibit short circuits or increased resistance within individual cells. As is also well known, such faults affect the ability of the battery containing one of these cells to provide the rated output when called upon, and may well cause the degradation of the remaining components of the battery.
Standby storage batteries are designed to deliver energy to a load over a relatively long period of time at a slowly declining voltage, in contrast with the short-duration, high discharge typically provided by automotive batteries. Each standby storage battery includes one or more chemical cells, with multiple cells being connected in series so that the overall voltage, measured across the battery terminals, is equal to the sum of the individual cell voltages. Individual batteries are further connected together in series to form a battery bank having the level of voltage for the particular station battery.
The voltage measured across the positive and negative terminal of a battery cell, is a characteristic of the chemistry for that cell. In lead-acid batteries, the voltage across the terminals for a single cell is about 2 volts, while in a nickel-cadmium cell, the voltage is about 1.2 volts. In each cell, positive and negative reactants are bound together into positive and negative plates. Plates of like polarity are attached to a rigid, metallic supporting strap, which is fitted with a terminal post for connection to external loads. The assemblies of positive and negative plates with their respective straps and terminal posts are suspended in a jar or similar container, containing an electrolyte, and the plates are separated so that no direct contact between them occurs. Contact between plates of dissimilar polarity would result in a short circuit, rapidly discharging the cell and rendering it ineffective. The containers containing the cells are closed with a cover however, the terminal posts protrude for the connection to the external load.
When an electrical load is connected to the terminals of the battery, a chemical reaction occurs between the electrolyte and the materials making up the battery plates to make an electrical current flow between the plates of opposite polarity and thus through the terminals and the load. The battery “discharges” by providing the DC current to the load, as the flow of active materials in the electrolyte and the plates equalize. By connecting a battery charger to the terminals of the battery, and effectively causing a reversed current to flow through the cells, between the oppositely charged plates, the reverse chemical reaction occurs and the battery becomes recharged.
A storage battery, like any source of electrical energy, has an internal impedance, which includes resistive, inductive and capacitive components. As the battery discharges, the current produces a voltage drop across the internal resistance of the battery in accordance with Ohms law. This voltage drop causes the voltage across the battery terminals to be somewhat less than ideal, i.e., the expected voltage, and the voltage drop consequently diminish the ability of the battery to power the load. The internal r
Garvey, Smith, Nehrbass & Doody, L.L.C.
Toatley Gregory
LandOfFree
Battery monitor and open circuit protector does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Battery monitor and open circuit protector, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Battery monitor and open circuit protector will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2900182