Why Siemens 7SR120 Directional Overcurrent Protection Relay | Reyrolle Are Important For Industries

The 7SR11 series of Siemens relays are well known for providing overcurrent and earth fault protection. Siemens directional overcurrent relay is a product largely used to provide main protection on feeders and interconnections. The device has the potential to give backup protection on items used in plants such as transformers. Siemens overcurrent relay is often the only protection installed on distribution system circuits overcurrent and earth fault protection. The directional control of the overcurrent & earth fault functions can be challenging but can be easily managed with the help of 7sr120 relays. Hence it is usually installed at a place where fault current can flow in either direction for better results. The highly flexible settings are available in the relay for current and time grading. This makes it compatible to function with all types of overcurrent protections without any trouble.

The relays are available in both single and four-pole variants which are covered in E4 cases. The device comes with the IEC61850 protocol option accommodated in an E6 case. The relays come with Integrated logic which helps the relay with the optimal configuration of the relay’s analogue inputs and binary input/output circuits. Users can easily access all the functions provided in the relay Metering, Protection, and Instrumentation via datacomms channels. Datacomms channels consist of a front USB port provided for local PC connection and rear electrical. It is also designated with an RS485 port that supports the remote connection. The 7sr120 relay is compatible with all types of overcurrent protection as it comes with highly flexible settings for current and time grading.

Protection Functions Of Siemens 7SR120

• Undercurrent (37) The under-current detection can be helpful against loss of load situations.
• Broken Conductor (46BC) A open phase condition on the circuit can be a big hurdle that is detected by the broken conductor detectors.
• Negative Phase Sequence Overcurrent (46NPS) helps when there is an unbalance in the phase currents caused by an unbalanced load or fault.
• Thermal Overload (49) these protective devices helps in cutting power when the motor draws extra current for a longer period.
• Overcurrent (50, 51) is the basic protection used for the protection of both transformers and feeders due to overcurrent or earth faults
• Earth Fault (50G, 50N, 50SEF, 51G, 51N, 51SEF) protects the electrical system from short circuits that occur from an inadvertent fault in the live conductor and the earth.
• Directional Control of Overcurrent & Earth Fault (67) helps in determining the direction of the fault. 
• High Impedance REF (64H) is used for detecting faults in reactor winding, transformer winding and stator winding of machines
• When an over/under voltage condition is mutilating protection is provided to the equipment through Under/Over Voltage (27/59).
• Negative Phase Sequence Voltage (47) is used to detect an imbalance in the network of line-to-line or for broken conductors missed by overcurrent or earth fault.
• Voltage Controlled Overcurrent (51V) is a backup function used to detect phase faults that occur in the line between the GSU and substation.
• Neutral Voltage Displacement (59N)

Supervision Function Of Siemens 7SR120

• CT Supervision (60CTS) is done to detect CT failure.
• Trip & Close Circuit Supervision (74T/CCS) provides continuous supervision to give a warning in case of loss in auxiliary supply or fault on the wire.
• VT Supervision (60VTS) keeps a check on all three voltage and residual voltage.
• An inrush Detector (81HBL2) is provided to monitor the line current.
• Circuit Breaker Fail (50BF) is designed to discover the failure of breakers that are shut when a tripping order is sent.

Control Function Of Siemens 7SR120

• Auto Reclose (79)

Monitoring Function

• Primary/Secondary Current Phases and Earth Direction
• Primary/Secondary Line and Phase Voltages
• Apparent Power and Power Factor
• Real and Reactive Power
• W Hr and VAr Hr Forward & Reverse
• Historical Demand Record
• Positive Phase Sequence (PPS) Voltage & Current
• Negative Phase Sequence (NPS) Voltage & Current
• Zero Phase Sequence (ZPS) Voltage

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Siemens is one of the most trusted and oldest leading MNCs in India thanks to its quality products for diverse types of power systems. To get the best deal on Siemens 7SR120 contact us as Reliserv Solution is the authorized Supplier and also Channel Partner of SIEMENS Make Numerical Relays, Automation Products, Power Quality Meters & Instruments, MV Switchgear Spares, PSS SINCAL Software. We Reliserv Solution are the leading Reyrolle products supplier and exporter in Mumbai, Maharashtra. We also provide a wide range of services & customized solutions for Industries & Panel Builders. Contact us at +917506112097 or mail us your requirements at [email protected]. We deal in a wide range of products in Siemens, to learn more about our Siemens Reyrolle Numerical Relay collection click here.