Glossary by "C"

  • 161

    C rate

    1. A charge rate that, under ideal conditions, is equal to the energy storage capacity of an electricity storage device divided by 1 hour. For example, a storage device that can store 5 kiloWatt-hours of electric energy has a C rate of five kiloWatts, also known as a C rate of 1.  And, a C rate of 5 means energy storage divided by 12 minutes. 2. 1 C is the charge rate necessary to charge a battery in one hour. 10 C charges in 6 minutes and 0.1 C charges in 10 hours. 3. C rate is the charge rate a) for a specific storage device/system or type, b) under ideal conditions, c) that is equal to the energy storage capacity of the device divided by 1 hour. For example, a storage device that can store 5 kiloWatt-hours of electric energy has a C rate of five kiloWatts, also known as a C rate of 1. A C rate of 5 for the same system means energy storage capacity of five kilowatt-hours divided by 12 minutes whereas a C Rate of 1/5 would indicate discharge of a 5 kiloWatt-hour storage device divided by five hours.

    Source: ESA Technical Working Group
  • 162

    California Public Utilities Commission

    Acronym(s): CPUC

    CPUC regulates investor-owned utility companies (IOUs) and sets the rates customers pay for electricity.  

  • 163

    Capacity

    See: Power

    The rate at which equipment can either generate, convert or transfer energy.

    Source: ESA Technical Working Group
  • 164

    Capacity emergency

    A capacity emergency exists when a Balancing Authority Area

  • 165

    Capacity factor

    A value indicating the average percentage of full capacity used over a given period of time. For example, a generating facility which operates at an average of 70% of its normal full capacity over a measured period has a capacity factor of 0.7 for that period.

    Source: ESA Technical Working Group
  • 166

    Capacity firming

    Use of storage to provide energy to fill-in when variable generation (i.e. solar and wind) output is below the generator’s rated power output; done to provide constant power output.

    Source: ESA Technical Working Group
  • 167

    Capital expenditures

    Acronym(s): CAPEX

    All costs associated with design, purchase, installation/construction and financing of investments in/purchase of capital equipment.

    Source: ESA Technical Working Group
  • 168

    Cascading

    The uncontrolled successive loss of system elements triggered by an incident at any location. Cascading results in widespread electric service interruption that cannot be restrained from sequentially spreading beyond an area predetermined by studies.

  • 169

    Cascading outage

    The uncontrolled successive loss of bulk electric system facilities triggered by an incident (or condition) at any location resulting in the interruption of electric service that cannot be restrained from spreading beyond a pre- determined area.

  • 170

    Characteristic voltage

    The inherent voltage at which the storage system operates. For electrochemical batteries; the inherent voltage of individual cells, which is driven by the underlying chemical reaction(s) within the cell.

    Source: ESA Technical Working Group
  • 171

    Charge

    The process of injecting energy to be stored into the storage system.

    Source: ESA Technical Working Group
  • 172

    Charge rate

    The rate at which storage can be charged.

    Source: ESA Technical Working Group
  • 173

    Circuit recloser

    See: Recloser
    Source: ESA Technical Working Group
  • 174

    Coalition to Advance Renewable Energy through Bulk Storage

    Acronym(s): CAREBS

    CAREBS promotes energy storage and provides a policy voice for the energy storage community.

  • 175

    Cogeneration

    Generation of useful electric and heat energy using the same conversion system (e.g. internal combustion engine, combustion turbine or fuel cell).

    Source: ESA Technical Working Group
  • 176

    Combined cooling, heating and power

    See: Cogeneration
    Acronym(s): CCHP
    Source: ESA Technical Working Group
  • 177

    Combined cycle gas turbine

    Acronym(s): CCGT

    Combined cycle gas turbine plants utilize more than one cycle to generate electricity with waste heat used to make steam, generating additional electricity through a steam turbine.

  • 178

    Combined heat and power

    See: Cogeneration
    Acronym(s): CHP
    Source: ESA Technical Working Group
  • 179

    Competitive power supplier

    An entity that owns and/or operates one or more independent power facilities that are not regulated under the traditional terms. These suppliers are regulated and monitored by the Federal Energy Regulatory Commission (FERC).

  • 180

    Conservation voltage

    See: Conservation voltage reduction
  • 181

    Conservation voltage reduction

    Acronym(s): CVR

    Operation of T&D equipment at the minimum allowable voltage to improve energy efficiency and/or to reduce peak demand. Most CVR schemes contain two fundamental components: reactive power compensation and voltage optimization. Reactive power compensation is achieved through the operation of shunt capacitors in order to maintain the power factor at the substation transformer within a prescribed band. Voltage optimization is achieved through the operation of substation voltage regulators in order to regulate the voltage at specific end of line points within a prescribed range.

  • 182

    Constant-current charge

    1. For batteries; a charging process during which the electric current into the battery is constant. 2. For batteries; a charging process during which the electric current into the battery is constant. Charging is stopped when the battery is fully charged and constant-voltage charging is used.  

    Source: ESA Technical Working Group
  • 183

    Constant-voltage charge

    For batteries; a charging process during which the voltage applied to a battery’s terminals is constant.

    Source: ESA Technical Working Group
  • 184

    Constrained facility

    A transmission facility (line, transformer, breaker, etc.) that is approaching, is at, or is beyond its System Operating Limit or Interconnection Reliability Operating Limit.

  • 187

    Contingency

    The unexpected failure or outage of a system component, such as a generator, transmission line, circuit breaker, switch or other electrical element.

  • 188

    Contingency reserve

    1. The provision of capacity deployed by the balancing authority to meet the disturbance control standard (DCS) and other North American Electric Reliability Corporation (NERC) and regional reliability organizations’ contingency requirements. 2. Reserves set aside to support the transmission system in the case of the worst foreseeable contingency event (often referred to as N-1)  

  • 189

    Contract path

    An agreed upon electrical path for the continuous flow of electrical power between the parties of an Interchange Transaction.

  • 191

    Control performance standard

    Acronym(s): CPS

    The reliability standard that sets the limits of a Balancing Authority

  • 192

    Cost-of-service

    The total cost incurred by the utility to generate, transmit and deliver electricity and to provide customer service.

    Source: ESA Technical Working Group
  • 193

    Critical assets

    Facilities, systems, and equipment which, if destroyed, degraded, or otherwise rendered unavailable, would affect the reliability or operability of the Bulk Electric System.

  • 194

    Critical peak pricing

    Acronym(s): CPP

    A program involving “high” or “very high” prices (relative to normal prices) that are assessed during “critical peak” periods (when demand is at or near supply).

    Source: ESA Technical Working Group
  • 195

    Current

    See: Electric current
    Source: ESA Technical Working Group
  • 196

    Current density

    The amount of current per unit area such as the amount of current flowing through a wired per unit of cross sectional area of the wire that is perpendicular to flow of current. Current density is a vector quantity whose direction is the same as the direction of current flow.

    Source: ESA Technical Working Group
  • 197

    Curtailment

    1. A reduction in the scheduled capacity or energy delivery of an Interchange Transaction. 2. A temporary reduction in customer load that occurs or that is imposed because demand exceeds the capacity.

  • 198

    Customer facility charge

    An charge that is part of an end-use customer’s electricity bill that may be used to cover—among other utility costs— cost to maintain utility facilities and infrastructure needed to provide electric service to the respective customer. Charges may include, for example, T&D equipment, accounting, meter reading and site-specific services.  Facility charges may also be a way to combine several small fixed-cost charges associated with maintaining a customer’s energy account.

    Source: ESA Technical Working Group
  • 199

    Cutoff voltage

    See: End-point voltage

    Voltage at the end of useful discharge.

  • 200

    Cycle

    See: Cycle life

    One sequence of storage charging and discharging. Also known as charge-discharge cycle.

    Source: ESA Technical Working Group
  • 201

    Cycle life

    The number of charge-discharge cycles after which storage becomes inoperable or unusable for a given application. In practice, storage may be inoperable or unusable when it can still deliver a portion of its initial rated energy and/or power rating.

    Source: ESA Technical Working Group