increase uptime using digital rsds - mark allen group · 2017. 2. 22. · for example, devices such...

Increase uptime using digital RCDs. Build it in.

Circuit Protection – Digital RCDsWhite Paper

31589 WP EN CP Digital RCD CMYK P1.indd 1 23/05/2016 13:29:29

2 EATON – Digital RCDs

White Paper WP012005ENEffective June 2016

A digital worldMaximizing uptime is vital for companies to remain competitive in today’s market. For example the cost of downtime on a machine can easily run in to the tens of thousands. Many businesses operate with minimal reserve stock, while processes are typically running at over 95% uptime to meet demand. For these reasons, downtime can quickly lead to loss of shipments, impacting turnover and customer confidence.

Circuit protection, and in particular residual current devices (RCDs) and the latest digital RCDs can help machine building companies offer their manufacturing customers increased uptime as they offer monitoring and pre-warning capabilities. This technology provides information about the machine’s health to the maintenance personnel and to the network and therefore facilitates preventive maintenance, ultimately leading to less machine downtime.

Further increases to a machine’s reliability can be made by installing the right technology according to appropriate standards and safety requirements. Here it is vital for machine builders, especially for those who export worldwide, to work with partners that know the international requirements, and can offer one product that is world market product.

Not only is operational efficiency and productivity increased through the improved diagnostics available with today’s digital technology, but with the right circuit protection technologies, the safety and protection of man and the machine is also increased. RCDs protect against damaging electrical faults: residual and leakage currents can be caused by fault conditions that occur within an electrical circuit. These can have devastating effects on the human body, causing cardiac arrest or worse, and lead to machine failure, which affects the bottom-line. They can also lead to fires.

In this paper Peter-Lukas Genowitz, Product Manager RCCB at Eaton, reviews the latest developments and discusses the advantages and benefits available from applying digital technology to RCD devices. With the correct implementation of RCDs and help from specialists, machine builders can increase the performance and safety of their equipment, ultimately leading to increased productivity for their customer. It is the second of three white papers that explores the topic of residual current.

Introduction

The IEC 60364 and the respective national standards or the NEC (National Electrical Standard) for North America provide the base for the installation of Low Voltage electrical systems worldwide.

Beyond that, the IEC 60204-Series has a fundamental significance for industrial installations because it addresses the electrical safety of machines. According to the standard, the electrical equipment of a machine must fulfil the safety requirements that are identified during the risk assessment of the machine.

The standard must be taken into account in all situations involving the electrical equipment of machines in order to ensure suitable safety measures for people in the context of risk assessment, and to maintain an acceptable level of performance and efficiency of machines and their equipment.

It is a harmonised standard to the machinery directive and the use of it in designing machines will give the machine builder the conformity to the corresponding essential health and safety requirements (EHSR) of the machinery directive 2006/42/EC.

Presently, in many TN networks laid out according to regulations, only protective earth is executed as fault protection. This is understandable, but it means that many hazardous situations identified in a risk assessment compliant with IEC 60204 are not properly addressed. For example, a fault in the electrical equipment which would result in the possibility of an electrical shock for a person or a fire.

A practical example is a fire hazard caused by earth leakage currents below the trip point of the overload protection. This can happen with type NH fuses or circuit breakers with type D characteristics which have very high short-circuit trip levels and are typically used for electrical forklift charging stations. In industrial applications cable damage is a frequently encountered issue and an RCD can significantly reduce the risk of fire in situations where undetected earth leakage currents pose a safety risk.

Based on practical experience, it is proven that RCDs help to reduce the hazard potential. The latest digital RCDs go beyond this to also improve the reliability of the machine and to reduce the failure probability.

Another aspect recommended by the IEC 60204 is preventative maintenance, and through using the latest digital RCD technology, machine builders can implement these measures. The pre-warning features of the latest digital RCBOs and RCCBs can detect creeping fault currents enabling users to be aware of an imminent failure before it occurs, and therefore take the necessary precautions and actions to prevent the failure.


3EATON – Digital RCDs


Digital RCD typesRCDs have been available for decades, reliably protecting man and machine. The first patents were received by Prof. Dr. Biegelmeier in 1957, and further development ensued with the first permanent magnet tripping unit being developed in 1965 – this is the heart of the modern RCD. The first digital RCD Type B and B+ technology was available in 2014. Their advantages in protecting man and machine are widely known, but digital RCDs are heralding a new era in preventative maintenance.

1. Digital RCDs the perfect choice for machinery builders

Digital RCDs combine protection functionality with a set of digital features – unique within the circuit protection market – that work together to provide maximum circuit status information and increase the protected system or machine’s availability. The digital technology is applied to both RCCBs and RCBOs.

The devices continuously measure the residual current value in real time, and use the results to drive local pre-warning LEDs and remote pre-warning potential-free outputs. These pre-warnings allow maintenance staff to resolve creeping problems before they lead to interruptions or failures. System status is always available at a glance, and cost savings accrue due to the reduction in unscheduled service callouts. Further savings arise because test intervals can be extended to once a year only.

System availability is further enhanced, as the digital protection devices have short time delays and optimised tripping thresholds to ensure that malfunctions of brief duration do not cause nuisance tripping and loss of system availability.

Fig.1: Digital RCDs alert maintenance staff of problems before a blackout occurs.

2. Digital RCCB

The digital RCCB is equipped with a voltage independent protection function and voltage dependent digital features. Digital RCCBs are available as Type A, U, B, Bfq and B+.

The digital RCCB offers a local pre-warning via LEDs on the front and a potential-free auxiliary contact. With the potential-fee auxiliary contact the pre-warning can be easily forwarded to a monitoring system.

3. Digital RCBO

The digital RCBO is a voltage dependent RCD. This means the protection function and the additional digital features are voltage dependent and must be supplied with a certain level of voltage. Digital RCBOs are available as Type A.

The digital RCBO is as the RCCB equipped with a local pre-warning via the LED on the front. In addition it is also equipped with a service mode for an easy and exact visualization of the actual earth leakage current downstream of the RCBO.

Fig.2: Local pre-warning via the LEDs + remote pre-warning via a potential free output.

Permanent light green

Permanent light yellow

Permanent light red

Flashing yellow/red

Status indication LED

Local indication

Red / Yellow / Green

Normal operation

The measured residual current is higher than 30% of the nominal tripping value.

The measured residual current is higher than 50% of the nominal tripping value.

Check the device with test key. If the LEDs are still flashing check the direction of connection (supply side/load side).

Remote pre-warning

Local pre-warning

Local pre-warning + service mode


4 EATON – Digital RCDs


RCDs Type B, Bfq and B+In general Eaton recommends to use at least a RCD Type A to provide the necessary protection level for industrial applications.

Beyond that, Type B RCDs are recommended for fire hazard and additional protection in connection with speed controlled machines or rather frequency inverter applications in general. The occurring smooth DC current negatively influences or incapacitates the detection of Type AC or A RCDs and so in the worst case the protection is disabled.

Type B residual protective devices can detect sinusoidal AC and pulsating DC as well as smooth DC fault currents, making them suitable for all kinds of applications and occurring waveforms according to IEC/EN 62423. Trigger conditions for fault currents with different frequencies up to 1 kHz are defined for Type B residual current devices.

Type Bfq RCDs comply with Type B requirements (IEC/EN 62423) while being designed for use in circuits that include frequency converters for speed-controlled drives. They have specially-adapted tripping curves, defined up to 50 kHz and are designed to avoid nuisance tripping.

Type B+ RCDs comply with the requirements of VDE 0664-400 and have a frequency tripping response defined up to 20 kHz. Their maximum tripping current at higher frequencies is limited to 420 mA. This provides superior protection from fire risk caused by ground fault currents in applications with electronic drives. This is especially requested in agricultural applications to avoid any fires caused by high frequent earth leakage currents.

The following chart best describes how to select the most appropriate RCD for the application.

Lean connectivity for protective devices RCDs are an important component for reducing downtime, but machine builders and installers can increase uptime further and make savings of up to 30% by integrating them within a Lean Automation environment.

For example, devices such as MCBs, RCCBs and RCBOs can be quickly and easily connected to intelligent wiring and communications technology through Eaton’s SmartWire-DT MCB/RCD module.

This makes additional I/O level and wiring redundant, enabling machine builders to reduce installation time and costs. Through using this system, the status (on, off, tripped) of the protective devices is made available within the control or monitoring system of the machine or the power distribution network. This supports the service and maintenance teams continuously with information about the system, helping them to react immediately to problems and to keep the system downtime to a minimum.

Applications with:

• Electronic consumers (switching power supply…),• Frequency converters (Pumps, medical devices, elevators, escalators, air condition and ventilation systems …) • DC systems (photovoltaic systems and ups units…)

Applications with PV systems, battery banks, UPS units, EV charging:

• Frequency converters for motor applications

• Speed regulated machine tools

Industrial applications which contains high-power frequency converter controls as:

• Frequency converters for motor applications

• Speed regulated machine tools

Fire risk applications as:

• Petrol station

• Agriculture

• Paint shop

• Depots and warehouses

• Biogase plants

• VDE 0664-400

RCCCB Type B+

according VDE 0664-400 for supire fire protection (max. tripping current of 420mA for frequencies up to 20 kHz)

RCCB Type B

(acc. IEC 62423)

Standard type, sensitive to all residual currents

RCCB Type Bfq

(acc. IEC 62423)

Non-sensitive against system caused earth leakage currents at high frequencies


5EATON – Digital RCDs


ConclusionsMachine builders need to ensure equipment consistency and standardization across all of their installations worldwide, therefore enabling their customers to realize the benefits of a highly reliable machine which increases their productivity while protecting their machines and staff.

An effective response to this challenge is to source products from a truly international supplier with the capability to manufacture at multiple sites around the world, yet have the ability to manufacture to the same internationally-recognized, standardised designs. Additionally, organizations with one product version in all locations need just a single set of work instructions and procedures, while purchasing is more efficient and spare part stock levels can be reduced.

Machine builders specifying circuit protection equipment (in particular RCDs) and seeking to minimise costs while offering

high performing, reliable machines have a number of possible strategies; these relate to the equipment’s technical features along with a wider range of equally important factors. An ability to specify and receive exactly the same products, albeit with controlled local variations, anywhere in the world simplifies maintenance and operational procedure planning.

This white paper has outlined how digital RCDs offer many opportunities for cost-effective maintenance with increased productivity, especially on very large or multi-site operations. Information on the status of the RCD is presented to maintenance staff where they need it, enabling them to take preventative action on potential faults.

For more information on Eaton’s RCDs visit: www.eaton.eu/en/cp/rcd

Example: Savings in every step of the life cycle

Intelligent Wiring

Conventional Solution

Saving 30%

Planning / Engineering

Material Wiring Commissioning Maintenance

Fig.3: Savings accruing from migration to Intelligent Wiring

Downtime can be reduced further by integrating RCDs with Eaton’s SmartWire-DT line


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Eaton Industries GmbHHein Moeller Str. 7-1153115 BonnEaton.eu

© 2016 CorporationAll Rights ReservedPublication No. WP012005EN / 06/2016

Eaton is a registered trademark.

All other trademarks are property of their respective owners.


increase uptime using digital rsds - mark allen group · 2017. 2. 22. · for example, devices such...

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