Measuring Relays

RXEDA 1 is a microprocessor based time-overvoltage relay. The relay can be used for AC or DC. The AC input can be single- two- or three-phase, with or without neutral.

The relay may also be used as an instantaneous single-phase undervoltage relay. In case of three-phase undervoltage applications using one relay only, the relay will set required undervoltage in all phases in order to operate.

Since the relay does not need a separate auxiliary DC supply, it is suitable as a replacement for electromechanical relays.

RXEDA 1 has a built in timer and a LED indication of the time-delayed trip function. A starting output can be used as an alternative to having both outputs operated after the time-delay.

• Setting voltage ranges are 20-300 V DC and 15-210 V AC, 15-400 Hz
• Setting time range of 0-10 s definite time
• Two output change-over contacts; one for start and one for time function or both for time function
• High resetting ratio; > 97 %
• No auxiliary voltage required 

RXETB 1 operates in case of fuse failure in one or two phases of a three-phase system or if the voltage in one phase drops below 40 % of rated voltage and the other two phases have rated voltage. Fuse failure in all three phases is unlikely to occur, therefore the RXETB 1 relay is sufficient in most cases.

The measurement principle is based on a comparison between the neutral point of the voltage transformer and an internal neutral point derived from the three phases. When a voltage difference is detected, the two output relays, each with one change-over contact, operates.

By a knob at the front, the operation can be set to be delayed up to 10 seconds. During operation, a red LED is lit at the front of the relay.

Unbalanced phase-to-phase connected loads is not a problem due to the high remaining voltages. If the relay operates because of a voltage drop in one phase, it will reset when the voltage exceeds 75 % of rated voltage.

• Detects single- or two-phase fuse failures
• Is used together with fuses only
• Detects voltage unbalance in a three-phase group
• Settable operate time delay 0-10 s
• Operation is indicated by a red LED
• Used to give delayed alarm of fuse failure in ac supply circuit e.g. to synchronizing and energy metering equipment 

The compact current relay RXHB 411 has a wide application range as an important part of the backup protection for feeders and lines, transformers, capacitor banks, electric boilers as well as for generators and motors.

• Three-phase compact numerical breaker failure relay
• Single- and three-phase breaker failure protection
• Pole disagreement protection

• Basic version
• Basic version together with overcurrent and earth-fault protection
• Basic version together with binary I/O option
• Basic version together with overcurrent and earth-fault protection and binary I/O option

• Phase overcurrent protection with two stages and definite time delay
• Earth-fault protection with two stages and definite time delay
• 4 additional inputs and 4 additional outputs 

The four overcurrent and earth-fault relays RAHL/RXHL 401, 411, 421 and 422 are intended for power system applications and as backup to e.g. the 650 or 670 series terminals at all system voltage levels including EHV. All time-curves are provided according to IEC 60225-3, the thermal replica overload function and the RI and a special logarithmic curve for earth-faults in EHV systems are also available. Intermittent phase- and earth-faults can be detected. The relays are also intended for retrofit and replacement of earlier electromechanical and static relay designs.

• Three stages for phase overcurrent I>, I>>, I>>> alarm and trip functions
• Three stages for earth-fault alarm and trip functions
• Supersedes RXIDK 4 and RAIDK 400

• Three stages of three-phase time-delayed or instantaneous overcurrent protection, I>, I>>, I>>> alarm and trip functions
• Three-phase thermal overload protection, Q> alarm and trip functions
• Three stages of time-delayed or instantaneous earth-fault protection, IN>, IN>>, IN>>> alarm and trip functions
• Breaker failure protection, three phases and neutral current detection, selectable timing logic and retrip for single & three-pole trip applications
• Pole disagreement function based on separate phase current level measurement
• Autoreclosing, up to 4 attempts (option)
• Extra I/O board with 4 optocoupled inputs and 4 relay outputs (option)

• Three stages of two-phase time-delayed or instantaneous overcurrent protection, I>, I>>, I>>> alarm and trip functions
• Three-phase thermal overload protection, Q> alarm and trip functions
• Three stages of time-delayed or instantaneous directional or non-directional earth-fault protection for effectively earthed networks, IN>, IN>>, IN>>> alarm and trip functions. - Polarising voltage down to 0.5%. - Settable characteristic angle from 0° to 90°.
• Breaker failure protection, three phases and neutral current detection, selectable timing logic
• Pole disagreement function based on separate phase current level measurement
• Autoreclosing, up to 4 attempts (option)
• Extra I/O board with 4 optocoupled inputs and 4 relay outputs (option)

RXIB 24 is a static, high-speed ac overcurrent relay generally used where high-speed and consistent operate and reset times are required. It's speed and consistency make the RXIB especially suitable for breaker failure applications where it is important that the set breaker failure time is not unduly influenced by variations in operation or reset time of the current-measuring relay.

• Operate time 4-15 ms
• Resetting time 5-11 ms
• 10 mA to 15 A total range for four models
• Low CT burden and high overload capacity 

The current measuring relay type RXIG is a static, instantaneous ac current relay which can be used as over- or undercurrent protection. The instantaneous and time delayed overcurrent protections with RXIG are used in a number of different applications, such as:

• short-circuit protection
• earth-fault protection
• capacitor bank unbalance protection
• generator interturn short-circuit protection
• blockable overcurrent relays for busbar protection
• special applications, such as blocking of tap changer regulation

• RXIG 21 with straight frequency characteristic
• RXIG 22 which has reduced sensitivity to higher frequencies
• RXIG 28 with extra low ac power consumption

The overcurrent protections RAIG are built up based upon the overcurrent relay RXIG 2. RAIG is available in several versions, with and without time-lag relay and with different duty on trip outputs.

• Test switch and trip indication included as standard
• Version with heavy- and medium-duty trip output
• Total setting range of 2,5 mA to 45 A
• High reset ratio enables a setting close to maximum service values
• High continuous current carrying capacity 

RXIDK 2H is a single-phase microprocessor based time-overcurrent relay that is available in multi-phase and earth-fault assemblies RAIDK. The RXIDK 2H has simple setting knobs and selector-switches for different inverse and fixed time delay overcurrent characteristics and operate values and time delays. It is used as short-circuit and earth-fault protection for all types of objects in the network.

The available time-lag characteristics and the short recovery times, together with independent measuring elements in each phase and for earth-faults, ensures suitability on networks of major importance, where selectivity and short backup tripping times are essential. It has four LEDs on the front for start, trip and self-supervision indication.

RXIDK 2H is pin compatible with the obsolete RXIDF 2H relays and is therefore offered as a replacement part.

• Independent measuring elements
• Three versions with different current ranges and wide setting ranges
• Versions with built-in test switch, DC/DC converter and heavy-duty trip relays are available
• Available with optional built-in filters for different frequency characteristics 

RXEG is a static voltage measuring relay that can be used for over- or under-voltage protection. The relays require a DC auxiliary supply for operation. Models suitable for different auxiliary voltages and input measuring quantities are available.

RXEDK 2H is a microprocessor based time-over/undervoltage relay with two measuring stages, which are switchable for over- or undervoltage functions independently of each other.

Stage 1 is programmable for two different time functions; definite time characteristic and inverse time characteristic.

Stage 2 has a definite time characteristic, settable from 0 to 10 s.

RXEDK 2H can be used in a number of different applications, such as; neutral point voltage-, overvoltage-, flash-over-, undervoltage- or stator earth-fault protection. The optional built in filters provide extended application possibilities. For example; A model measuring the third harmonic is available. Other frequencies of interest may also be quoted.

• Wide setting ranges in two measuring stages
• Built in operating time delays for both stages
• Over- and undervoltage setting selectable for both stages
• Allows setting close to maximum service values due to high resetting ratio
• Available with optional filters for different frequency response
• Low burden