Category: Industry Trends

Overview of the new VD4 Medium Voltage Circuit Breaker

The new VD4 Medium Voltage Circuit Breaker is the perfect combination of vacuum interrupter design and manufacturing technology with resin-embedded pole plates and technical excellence in circuit breaker design, engineering and production.

The VD4 medium voltage circuit breaker uses vacuum interrupters embedded in resin pole plates.

Embedding the interrupters in resin poles makes the circuit breaker poles particularly robust and protects the interrupters from shock, dust build-up and moisture.

A vacuum interrupter consists of a contact and an interrupting chamber.

Vacuum interrupters Vacuum circuit breakers do not require an interrupting and insulating medium. In fact, the interrupter chamber contains no ionisable material.

In any case, the arc generated when the contacts separate consists entirely of melted and vapourised contact material.

The arc is supported by external energy until the current disappears near its natural zero point.

At this point, the load density decreases rapidly and the metal vapour condenses rapidly, leading to an extremely rapid recovery of the dielectric properties.

The vacuum interrupter thus regains its insulating capacity and its ability to withstand transient recovery voltages, and the arc is finally extinguished.

Due to the high dielectric strength achieved in a vacuum even at short distances, circuit interruption is guaranteed when the contacts separate a few milliseconds before the current passes through the natural zero point.

The special geometry of the contacts and the materials used, as well as the limited duration of the arc and the low voltage

guarantees minimum wear and a long service life of the contacts. In addition, the vacuum prevents oxidation and contamination of the contacts.

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.

In addition to isolating contacts for connecting auxiliary circuits and flexible cables with plugs, the

The tractable circuit breakers are also equipped with a www.cniacs.com 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

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, www.cniacs.com 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.

Service safety

With a full range of mechanical and electrical locks (available on request), it is possible to build safe distribution switchgear with VD4 circuit breakers.

Locking devices have been studied to prevent incorrect operation and to check the device while maximising operator safety.

Keyed locking or padlocking devices enable switching and/or racking-in and racking-out operations.

Racking out with door closed devices allow the circuit breaker to be racked in or out of the switchgear only when the door is closed.

Anti-breaking locks prevent breaking in of circuit breakers with different current ratings, as well as breaking in operations when the breaker is closed.

ACCESSORIES

VD4 circuit breakers are available with a comprehensive range of accessories to meet all installation requirements.

The operating mechanism has a standardised range of accessories and spare parts which are easy to identify and order.

The accessories can be easily fitted from the front of the circuit breaker. Electrical connections are made using plug and socket connectors.

The equipment is simple to use, maintain and service with limited resource requirements.

Operating Mechanism

The operating mechanism of the VD4 circuit breaker is designed to be simple and easy to use, with a wide range of customised accessories for quick and easy installation.

This simplicity gives the equipment a higher degree of reliability.

The operating mechanism is of the energy storage type and is fitted as standard with an anti-pumping device with appropriate locks to prevent incorrect operation.

Each operating sequence can only be activated if all the conditions to ensure its correct execution are met.

All types of VD4 circuit breakers have the same accessories.

– Highly reliable operating mechanism thanks to low component count due to mass-produced system

– Extremely easy to maintain

– The accessories are common to the entire series and are the same for both AC and DC applications

– Quick and easy installation or replacement of electrical accessories, as the cables are already equipped with plug and socket connectors

– Mechanical anti-pumping device as standard

– Built-in closing spring-loaded charging lever

– Protective cover for the opening and closing buttons that can be operated with special tools

– Padlock device on the operating buttons

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 www.cniacs.com 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

APPLICATIONS

The SPAJ 140 C combined overcurrent and earth fault relay is intended for use on solid earths,

The combined overcurrent and earth fault relay www.cniacs.com is used for selective short-circuit and earth fault protection of radial feeders in solidly earthed, resistance earthed or impedance earthed power systems.

The integrated relay consists of an overcurrent unit and an earth fault unit with flexible tripping and signaling facilities.

The overcurrent and earth fault relays can also be used for other applications where single, two or three phase overcurrent protection is required.

The SPAJ 140 C combined overcurrent and earth fault relay is part of ABB’s distribution automation concept, a complete solution for controlling and managing power systems.

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 www.cniacs.com 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