Dynamic Protective Device

In addition to opening when a fault is detected, dynamic protective devices also reclose to attempt to reestablish service. If the fault remains after a prescribed number of reclosings, the device may lock open the circuit. Reclosing is designed to reduce or eliminate the effects of temporary faults. Protective devices have a Basic Insulation Level (BIL) rating, which is a reference insulation level expressed as the impulse crest voltage of the nominal 1.2 x 50 microsecond wave. This is a measure of the ability of the insulation to withstand very high voltage surges.

The DESIGNBANK model name is used by the Work Function tool in Designer. It designates a banked feature in the network.

Electric Tracing and Feeder Manager both use the DYNAMICPROTECTIVEDEVICE model name to identify sources.

The FDRMGRPROTECTIVE model name should be assigned to any feature class that can be considered a fuse or dynamic protective device (e.g. circuit breaker, recloser, sectionalizer) by Feeder Manager.

Electric Tracing uses the PROTECTIVE model name to identify the features that may be returned as protective devices. Structural Analysis (Designer) also uses the PROTECTIVE model name.

The DynamicProtectiveDevice class (all subtypes) inherits attributes from the ElectricDevice and OvercurrentProtectiveDevice abstract classes. All model names assigned to these abstract classes should be assigned to the DynamicProtectiveDevice class as well.

Associations: None

Subtypes: Circuit Breaker, Recloser, Sectionalizer, Fault Interrupter. The use of subtypes is optional. The Subtype attribute can be removed if subtypes aren't used in the model.

Model Names: DESIGNBANK, DYNAMICPROTECTIVEDEVICE, FDRMGRPROTECTIVE, PROTECTIVE

Attributes:

BILRating: long integer - Code indicating BIL rating of DynamicProtectiveDevice; domain values include 95 BIL, 150 BIL, etc.

GroundResistance: double - Describes ground resistance of DynamicProtectiveDevice in ohms.

InterruptingMechanism: text - Type of interrupting mechanism that operates the contacts of DynamicProtectiveDevice.

InterruptingMedium: text - Code indicating interrupting medium that insulates contacts of DynamicProtectiveDevice; domain values include Air, Oil, Vacuum, etc.

SCADAControlID: text - ID of SCADA control, if present.

SCADAMonitorID: text - ID of SCADA monitor, if present.

Each DynamicProtectiveDevice subtype inherits attributes from ElectricDevice, OvercurrentProtectiveDevice and DynamicProtectiveDevice. In addition each subtype may also have its own attributes. The DynamicProtectiveDevice subtypes are described below.

Circuit Breaker

Circuit breakers detect excessive power demands in a circuit and self-interrupt when they occur. Mechanical switching devices equipped with a trip coil connected to a relay are designed to open under fault conditions. The contacts of the circuit breaker open and close by mechanical linkages manufactured from insulating materials and using energy from compressed air, electric magnets, or charged springs. An arc appears for a limited time during the interrupting process. Breakers switch circuits and equipment in and out of the system within two to five cycles of a fault measured from trip coil energizing to extinguishing the arc. An accepted duty cycle is two openings with a 15-second interval.

Circuit breakers are rated by voltage level, current interrupting capabilities, interrupting time, transient recovery voltage, insulation level, and trip delay. Closing resistors may be used to keep switching overvoltages within acceptable limits.

CircuitBreaker inherits the attributes of the classes ElectricDevice, OverCurrentProtectiveDevice, and DynamicProtectiveDevice. CircuitBreaker

Associations: CircuitSource, RelayControl

Subtypes: None

Attributes:

BypassSwitch: text - Code indicating presence of bypass switch on CircuitBreaker; domain values are Yes or No.

ClosingResistor: text - Code indicating presence of ClosingResistor; domain values are Yes or No.

Manufacturer: text - Code indicating manufacturer of CircuitBreaker; domain values include ABB/Westinghouse, General Electric, etc.

Model: text - Model of the circuit breaker.

SerialNumber: text - Circuit breaker serial number.

International Data Model

In addition to the attributes listed above, the following attributes are used by the international electric data model.

BreakingVA - Short circuit current breaking capacity for voltages in the rated voltage range (value is in Volt-Amperes)

CapacitiveBreakingCapacity - Breaking capacity for capacitive current (in Amperes)

GasVolumePressure - Pressure rating for interrupting medium (gas)

InstantaneousRelease - Describes instantaneous release properties of the circuit breaker

IntrinsicMakeTime - Minimum time needed to make (Seconds)

MakingCurrent - Short circuit making capacity (Amperes)

NoOfMakes - Maximum number of makes after power loss

NoOfShortCircuits - Maximum number of operations before lock out (auto reclosing breakers only)

Closing - Indicates whether the circuit breaker has automatic reclosing capability

RestrikingVoltage - The maximum rated interrupting voltage for capacitive current switching, above which an arc restrike is likely to occur during operation

VisualEarthIndicator - Indicates whether the equipment has a visual grounding indicator

Recloser

Reclosers are a type of oil switch that uses controls to sense a fault and de-energize the circuit, wait briefly, and then reclose the circuit to try and re-establish service. Reclosers can lock out (remain open) after a predetermined number of attempts to close. Minimum trip current is usually twice the normal load current rating of the coil.

Automatic reclosing devices can reduce the number of total network outages by 75 to 90 percent. The amount of current that flows at the installation point under full load conditions should not exceed what the manufacturer has rated the recloser to carry continuously.

Recloser inherits the attributes of the abstract classes ElectricDevice, OverCurrentProtectiveDevice, and DynamicProtectiveDevice.

Associations: CircuitSource, RecloserControl, RecloserUnit, RelayControl

Subtypes: Single Phase Hydraulic, Two Phase Hydraulic, Three Phase Hydraulic, Three Phase Electronic, Three Phase Relay

Attributes:

BypassSwitch: text - Code indicating presence of BypassSwitch on Recloser; domain values are Yes or No.

MountingType: text - Code indicating mounting type of Recloser; domain values include Pad Mounted, Pole Mounted, and Substation Frame.

TieSwitchIndicator: text - Code indicating presence of tie switch; domain values are Yes or No.

Sectionalizer

Sectionalizers are automatic circuit opening devices that are installed on the load side of fault-interrupting devices and count the fault-trip operations. Sectionalizers can be set to open after one, two, or three counts have been detected with a predetermined time span. Sectionalizers are used in conjunction with fuses and reclosers and may have inrush current restraint features to prevent a false count when lines are re-energized.

Sectionalizer inherits the attributes of ElectricDevice, OverCurrentProtectiveDevice, and DynamicProtectiveDevice.

Associations: SectionalizerUnit, SectionalizerControl

Subtypes: Single Phase Hydraulic, Two Phase Hydraulic, Three Phase Hydraulic, Three Phase Electronic

Attributes: No additional

Fault Interrupter

Fault interrupters can replace circuit breakers to protect transformers in substation or networks. Often used for high-side transformer protection, fault interrupters open (trip) at a preset current and programmed time delay to minimize fault damage downstream. Fault interrupters employ current transformers (CTs) to provide line current level information to electronic trip control. One set of CTs provides phase sensing, and another senses zero-sequence (ground) current. Contacts open and close using stored energy and can be tripped electronically, electrically, or manually. Interrupters don’t reclose automatically: contacts are closed through a remotely located switch or a trip-close handle on the tank.

Associations: None

Subtypes: None

Attributes:

GangOperated: text - Indicates whether devices can be operated as a group.

Manufacturer: text - Code indicating manufacturer of device; domain values include Bridges, Siemens, etc.

Model: text - Model of device.

SerialNumber: text - Device manufacturer’s serial number.

ShuntMechanism: text - Shunt mechanism that trips device.

TripCount: long integer - Number of trips before device opens the circuit.