The document compares electro-mechanical relays with numerical relays, highlighting the advantages of numerical relays such as eliminating mechanical parts, compact size, enhanced memory for fault storage, and compatibility with automation systems. Numerical relays provide better accuracy, require less maintenance, and enable efficient monitoring and diagnostics of electrical faults. The text emphasizes the importance of transitioning to numerical relays for improved operational reliability and effectiveness in power utilities.

2. Spring
Disc
Time Adjustment:
Tension controlled
Contacts
Core
Sensing Coil
Electro Mechanical (Start of Century)

3. -controller
Current SamplingB CA E
AC - DC
Conversion
Output Control
Steady state data
Relay Contacts
Crystal
Micro Controller Based (Late 80s)

4. -controller
Current SamplingB CA E
Direct AC
Sampling
Output Control
Steady state data
Relay Contacts
Crystal Serial Port To Outside world
A to D
Late 90s: Numerical Relay Technology

5. Disadvantages
• No Phase Angle information.
• No Frequency information.
Time Domain Representation
Time
Amplitude
Frequency
50Hz
Frequency Domain Representation
Numerical Relay

6. Electro Mechanical Relay
• It works on Mechanical Parts, Springs and their appropriate tensions, which are
temperature dependent for giving Protection Trip Accuracy
• It needs to be Periodically Removed, Cleaned & need to do Spring Adjustments with
Season Changes for Correct Tripping Time Results
Numerical Relay
• Above problems are eliminated since No Moving Parts
• All IDMT timings, High Set Tripping Timings are with software based CPU
• CPU is completely embedded & gives Microsecond Repeat Accuracy
• No Periodical services, adjustments etc. required
Why do we recommend Numerical Relay?

7. Electro Mechanical Relay
• Generally Electro-Mechanical Relays are separately used for individual Phases
• High Set Setting is having different mechanism
• It consumes more space in Panels which increases C&R Panel cost
Numerical Relay
• All Numerical Relays are compact in size
• All Protection functions are available in same relay
• The Numerical Relay is 20% in size of Electro-Mechanical Relays of same functionality
Why do we recommend Numerical Relay?

8. Electro Mechanical Relay
• Memory of previous Fault records, Actual Value of Fault Current, etc. are not possible
to store
• Only one Mechanical Flag is shown for Relay Operation & Phase Indication
Numerical Relay
• Numerical Relays have the Memory to store the events & last 5 faults with Date &
Time Stamping
• This information is very important to diagnose Fault Pattern, by which Relay can be
reset so that such fault possibility could be removed/eliminated
• This information helps to get uninterrupted Power Supply which helps in good
Revenue Earning for the Utility
Why do we recommend Numerical Relay?

9. Electro Mechanical Relay
• Electro-Mechanical Relays are non-communicable
• These relays cannot be used for Sub Station Automation & SCADA system
Numerical Relay
• Numerical Relays are Communicable with all Standard Protocols
• Numerical Relays can be used for Sub Station Automation & SCADA system effectively
Why do we recommend Numerical Relay?

10. Numerical Self Power Relay

11. Integrated Solutions:
Protection & Automation
• Protection Relays
• SAS SCADA
• Control & Relay Panels
• Traction Protection

12. THANK YOU
Web: www.ashidaelectronics.com Email: sales@ashidaelectronics.com