Relay Control

Protective relay systems detect and isolate faults.

Time-delayed phase and ground relays are coordinated with fuses and reclosers further out on the circuit. They are instantaneous units with inverse TCCs to coordinate with fuses and reclosers further downstream. Relays are usually set to trip feeder breakers and protect the fuse in the event of temporary faults beyond the fuse. CTs measure large currents as well as insulate relays from high-voltage circuits. The primary winding of the CT is connected in series with the circuit to be measured. The nominal current ratio of the CT is the inverse of the turns ratio.

A variety of relay protocols exist. Directional comparison relay systems are set in twos; relay A responds to faults to its right, and relay B responds to faults to its left. Both will respond simultaneously only if the fault is on the line they are both protecting. One communication channel informs A about the state of B, and another informs B about the state of A.

Phase comparison relaying uses a communication channel to compare information about the phase currents based on the fact that external faults are essentially equal in magnitude and opposite in direction while internal faults are in phase.

Associations: DynamicProtectiveDevice (only valid for Circuit Breaker and Recloser subtypes)

Subtypes: None

Model Names:

Attributes:

Field Name

Field Type

Description

CTRatio

text

Ratio of CT

CurveID

text

Identifier of TCC curve.

Hyperlink

text

Used to store a hyperlink path via standard Esri hyperlinking functionality.

InstantTripTapSetting

long integer

Value in amps of CT secondary current that will trip relay immediately.

Manufacturer

text

Code indicating manufacturer of RelayControl; domain values include ABB/Westinghouse, General Electric, etc.

Model

text

Relay Control's model.

TapSetting

long integer

Tap setting of relay.

TimeLeverSetting

double

Time dial setting; defines shape of TCC curve used.

QR code for this page

Was this helpful?