Transformer Protection
M-3311A (2, 3, or 4-Winding) Relay

Protect Transformers and Other Important Power System Apparatus

The M-3311A transformer protection relay provides you with the ability to meet or exceed ANSI/IEEE C37.91 standards with enhanced security.

Your Benefits:

Reduce project and ownership costs—

  • Standardization for two, three and four winding differential applications
  • Commissioning tools to speed factory acceptance testing and field start-up
  • Configurable and selectable elements to meet protection challenges for different winding types, CT connections, and grounding of transformers
  • Programmable I/O for advanced scheme logic applications
  • Meets ANSI and IEC relay compliance standards
  • Integral metering, event logging, communications and waveform capture

Enhance security and operational use—

  • Dual slope restrained differential, high-set unrestrained differential and restricted earth fault differential elements provide excellent unit protection
  • Unique 2nd and 4th harmonic restraint for enhanced security on transformer energizing (inrush detection). 5th harmonic restraint for security during overexcitation events
  • Overexcitation (V/Hz) element for extended asset protection
  • Undervoltage and underfrequency elements for load shedding applications
  • Phase and ground overcurrent elements for back-up protection
  • Optional breaker failure protection and breaker monitoring for each winding input

Provide Secure Unit Protection! The M-3311A Transformer Differential Relay meets the challenges of power plant, transmission and distribution differential applications. The primary objectives of the relay is to provide secure protection, economy and integration of functions. The relay uses element designs that enhance security against false tripping—helping maintain the integrity of your system.

Protection and More – The M-3311A provides protection against internal unit phase and ground short circuits, abnormal operating conditions, abnormal system conditions, uncleared system faults and breaker failure. This Integrated Protection Systems (IPS®) expands the efficiency of your operations by providing extended functions such as metering, monitoring, event logging, waveform capture (digital oscillography), and local/remote serial communications.

Scalable Application – Based on the number of windings, the M-3311A allows you to select the optimum balance of protection while keeping cost to a minimum.

Meeting Utility and Industrial Standards – The M-3311A meets pertinent ANSI, IEC, UL and CSA standards. This is helpful toward standardization for any utility or industrial application. Beckwith Electric is an ISO 9001 certified company.

Communications Ability – The M-3311A employs MODBUS RTU. The unit employs MODBUS RTU andDNP 3.0 for integration into power plant control systems and utility SCADA.

Ease-of-Use – The Integrated Protection Systems software (IPScom®) provides easy configuration, as well as setting and viewing of logs and data from the relay. All interactions are broken down into small, logical steps. The software can be used to print all configurations and settings to automate the recording process of each relay’s application.

Application Flexibility – Programmable I/O allows the elements to be linked to various output contacts, and to be blocked by control (contact sensing) inputs. This flexibility allows the M-3311A to meet various trip logics as mandated by each application. All elements can be disabled or enabled in order to custom match the exact protection requirements of a given project. The suite of elements can be adapted to meet different protection requirements due to winding types, CT arrangements and grounding.

In addition, many applications may be implemented, such as:

  • Fast bus protection using selective overcurrent element blocking
  • Underfrequency load shedding
  • Undervoltage load shedding
  • Failed feeder relay back-up
  • LTC blocking on fault conditions
  • Breaker failure protection
  • Alternate settings of back up relays for station/feeder cold load pick up, seasonality and other applications

Testing, Commissioning, and Event Investigation Tools – The M-3311A metering functions include sequence components, differential and restraining quantities, and vector diagram displays of the inputs. With these, it is easy and fast to verify proper relay setting and proper wiring of complete protection systems—from the instrument transformers to the relay, and everything in between! Improper phasing and polarity reversals are easily seen as high negative-sequence quantities. IPSplot®, our software program for waveform capture analysis, is available for a small extra cost, and provides comprehensive information for detailed event investigations. They also have IRIG-B inputs for coordinated time stamping with other devices.