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Operating mechanism type EL

The low speed of the contacts, the short running time and the low mass limit the energy required for operation and thus ensure extremely limited wear of the system. Circuit breakers

therefore require only limited maintenance.

VD4 circuit breakers have a mechanical operating mechanism with energy storage and free tripping. These features make opening and closing operations independent of the operator.

The operating mechanism is very simple to conceive and use, can be customised with various accessories and is quick and easy to install. This simplicity makes the equipment more reliable.

Structure

The operating mechanism and the magnetic poles are fixed to a metal frame which also serves as a support for the fixed circuit breakers.

The compact construction ensures robustness and mechanical reliability.

The tractable circuit breakers are also equipped with a bracket trolley for putting them into or taking them out of the switchgear or enclosure with the door closed.

– Vacuum interrupter technology

– Vacuum contacts protect against oxidation and contamination

– Vacuum interrupters embedded in resin poles

– The interrupters are protected against vibration, dust and humidity.

– Poles sealed for life

– Operation in different climatic conditions

– Limited switching energy

– Energy storage operating mechanism with anti-pumping device as standard

– Simple customisation with a full range of accessories

– Fixed and withdrawable

– Compact dimensions

– Compact dimensions Robust and reliable

– Limited maintenance

– Doors closed when circuit breakers are racked in and out

– Special locks on the operating mechanism and forklift truck prevent incorrect and dangerous operation

– High environmental compatibility

ABB Arc Extinguishing Principle for Arc Extinguishing Chambers

In a vacuum arc extinguishing chamber, the arc starts at the moment of contact separation and is maintained until zero current is applied and may be affected by magnetic fields.

Vacuum Arc – Diffuse or contracted after contact separation, a single melting point is formed over the entire surface of the cathode, generating the metal vapour that supports the arc.

A diffuse vacuum arc is characterised by expansion of the contact surfaces and uniform distribution of thermal stresses across the contact surfaces.

At the rated current of the vacuum interrupter, the arc is always diffuse. Contact erosion is very limited and the number of current interruptions is very high.

As the value of the interrupting current increases (above the rated value), the arc changes from a diffuse to a contracting type due to the Hall effect.

Starting at the anode, the arc contracts and gradually becomes defined with further increases in current.

In the vicinity of the area in question, the temperature rises, which causes thermal stress on the contacts.

To prevent overheating and erosion of the contacts, the arc needs to remain rotating. As the arc rotates, it becomes similar to a moving conductor through which current passes.

Spiral geometry of ABB vacuum interrupter contacts

The special geometry of the helical contact generates a radial magnetic field in all areas of the arc column and concentrates it around the circumference of the contact.

Spontaneously generated electromagnetic forces acting in a tangential direction cause the arc to rotate rapidly around the contact axis.

This means that the arc is forced to rotate and involves a wider surface than a fixed contracting arc.

All this makes contact erosion negligible, except for minimising thermal stresses on the contacts.

Most importantly, the arc extinguishing process can be controlled even in the case of extremely high short circuits.

ABB vacuum interrupters are zero-current interrupters, which do not produce any re-strikes.

At zero current, the current charge is rapidly reduced and the metal vapour condenses, thus restoring the maximum dielectric strength between the interrupter contacts in microseconds.

VD4 circuit breakers have passed the following tests to ensure the safety and reliability of the equipment when used in any installation environment.

– Type tests: heating, industrial frequency withstand voltage insulation, lightning impulse withstand voltage insulation, short-time and peak withstand voltage current,

Mechanical life, short-circuit current generation and breaking capacity, no-load cable disconnection.

– Individual tests: main circuit insulation at working frequency voltage, insulation of auxiliary circuits and operating mechanisms, main circuit resistance measurement, mechanical and electrical operation.

Brief Introduction

The SPAM150C Motor Protection Relay is a general purpose combination relay designed primarily for the protection of AC motors for a variety of applications.

It combines a large number of protection functions in one unit. The relay provides a complete set of protection against motor damage caused by various electrical faults.

The relay is also suitable for other equipment requiring thermal overload protection, such as cable or power transformer feeders.

Summary of Protection Functions

The relay thermal overload unit protects the motor against short- and long-term overloads. The maximum permissible continuous load depends on the setting value 1.

Normally this setting value is taken as the rated full load current (FLC) of the motor at an ambient temperature of 40°C. The motor can be overloaded for a short period of time if the motor is not loaded.

When the motor current increases to 1.05I under the above conditions, the thermal overload unit starts after a certain delay.

If the ambient temperature of the motor is below 40°C for a long period of time, the setting value I. can be set to .05…1.10 times the full load current (FLC) of the motor. 1.10 times.

The short-time overload phenomenon mainly occurs during the starting process of the motor. The motor is normally allowed to start twice under cold conditions and once under hot conditions.

One start is permitted under hot conditions, therefore, depending on the starting time of the motor, an integrating value t determining the characteristics of the thermal overload unit can be derived.

This value can be easily determined from the time/current graph in the hot state. t curve is selected from the starting current versus the corresponding starting time (with an appropriate margin).

The t-curve is selected from the starting current versus the corresponding starting time (with an appropriate margin). Using the same value of t, the total permissible starting time of the motor under cold conditions can be found from the cold curve.

Function

– Three-phase, low-setting phase overcurrent device with timed or inverse definite minimum time (IDMT ) characteristics

– Three-phase, high setting phase overcurrent device with instantaneous or timed characteristics

Operation

– Low-level ground fault device with timed or inverse deterministic minimum time (IDMT) characteristics

– High-level ground-fault unit with instantaneous or definite-time operation

– Built-in circuit breaker fault protection

– Two heavy load relays and four signal output relays

– Matrix of output relays for routing the start or trip signals of the protection stage to the desired output relays

– Local display of measured values, set values and data recorded during faults

– Reading and writing of set values via local display and front panel pushbuttons or via the serial interface and fiber optic bus of the higher-level system

– Self-monitoring system for continuous monitoring of electronics and microprocessor operation

Microprocessor operation

– Powerful software support for relay parameterization, reading of measured and logged values, events, etc., and

Powerful software support for relay parameterization, reading of measured and recorded values, events, etc., and storage of readings

– Member of the SPACOM product family and ABB’s distribution automation system

– CE marking according to the EU EMC directive

Features

Integrated three-phase differential relay, overcurrent relay and earth fault relay

Stabilized three-phase differential relays provide winding short-circuit and turn-to-turn fault protection for two-winding transformers and generator-transformer units, and winding short-circuit protection for generators.

Earth fault protection for transformer windings on the HV and LV side according to the required principle:

Stabilized differential current principle, high impedance principle, calculated or measured residual current principle or neutral current principle

Three-stage overcurrent protection for transformer and generator as well as two-stage backup protection for earth fault protection.

Differential relays with operating characteristics that can be easily adapted to different applications Short operating times, stable operation even in the event of partial saturation of the current transformer.

Prevents unwanted operation in the event of faults and transformer inrush currents outside the protective field.

Blocking based on the ratio of the second harmonic to the fundamental component of the differential current prevents unwanted operation in the event of transformer inrush currents.

Blocking based on the ratio of the fifth harmonic to the fundamental component of the differential current prevents unwanted operation in the event of transformer overexcitation.

– If the ratio of the fifth harmonic to the fundamental component of the differential current increases at high overvoltages, this blocking condition can be eliminated

Double-winding transformer protection without transformers – digital vector group matching on HV and LV side

Wide range of CT ratio corrections – precise corrections via digital settings Sensitive phase current and phase angle displays for easy checking of measurement circuits