Overload Relay By R. B. Automation

Overload Relays

Introduction
Three Phase A.C. Motor are the largest prime mover
turning production wheels in Industries. Repeated breakdown means Huge
loss of production and loss of production means substantial investment
lost. Owing to frequent failure of Motors, the same become energy
inefficient adding to 1-2% to power bill. Starters how-so-ever
sophisticated claiming all protection do not provide protection against
premature failure of Motors, owing to single phasing, bearing failure,
locked rotor conditions and it is due to these reasons offending break
down of motors turning production wheels are traced to 50% single
phasing 50% bearing failure, inspite of adequately planned preventive
maintenance. S.S. Electronic overload Relays gives 100% protection
against all the reasons contributing to premature failure of Motor e.g.
single phasing current unbalances, voltage unbalances, phase failure
sudden High voltage, sustained Low voltages, overloading, bearing
failure, Misalignment, locked rotor condition. Impaired ventilation.
High Duty. Cycling etc. and at the same time saving energy worth Rs.
150 per motor per annum. Inverse current time characteristic enhances
operating life of Motor also as it does not allow the insulation of
Motor to be baked or aged keeping temperature with in thermal endurance
limits of Motor winding insualtion.

As per ISI and other standards, the negative sequence current sensing
is best principle for Single phasing Protection as protection is
provided for complete system i.e. upstream and downstream. Normally no
load current of Motor is 30% of its full load current, considering
above condition, single phasing protection has been designed to operate
even at no load condition of Motors. The relay has got capabilities to
accurately track overloading characteristic of Motor, with inverse
current time characteristics (Factory Set) which is the best protection
never before introduced. Owing to energy saving feature, the
convention  erratic, energy inefficient. Thermal over load relays
incorporated in starter are now being replaced with S.S. Hi-Tech Energy
saving electronic overload relay by productivity and energy conscious
Industrial leaders of reputed organizations.

The relays are manufactured in current range of 8-20 Amp, 16-40 Amp,
32-80 Amp & 80-200 Amp. reducing drastically store inventory of
the company.

Ultra Upgraded Protection of Three phase A.C. Motor From

Single Phasing (Negative Sequence Current)Current unbalancesVoltage unbalancesPhase Loading(Inverse Current Time Characteristics)Locked rotor conditionApplication Jammingbearing FailureMisalignmentsSustained VoltageHigh Duty CyclingImpaired VentilationSudden High Voltage.

Salient Features

Saves Substantial EnergyPrevents FirePay back time less than a yearPin Point & visually displays various faults reducing production Machine detentionWider ampere range reduces store inventoryAuto Manual resetImmune to System HarmonicsLife Expectancy over eleven yearsFail Safe.

Technical Specifications




System Voltage

415 V3 Phase +- 10%



System Frequency

50 Hz +- 3%



Trip time delay for single phasing
& Reverse phasing


2 to 10 seconds



For overload

Inverse current time characteristic



Aux. Power

3 Va



Output contact

1 N.C. (Potential Free)



Output Contact rating

Continuous 5 Amp. at 240 V AC & 1
Amp at breakdown Amp. at 415V at
0.5 P.F.



Duty Cycle

Continuous



Life Expectancy

Above Eleven year



Fail Safe

Relay is energized in Healthy
condition & trips

On phase failure, reverse phase,
overload, bearing failure, locked
rotor or interruption in Aux. Supply



Recommended Wiring

1.5 M.S. Square with fork type lug



Terminal

Phenolic moulded strip High Barrier



H.V. Test Voltage

2KV AC. 50Hz, 1 minute or 2.5 KV,
AC, 50Hz for 1 second between
mounting plate & any terminal



Insulation Resistant

Better then 100 M. Ohm at 500
V.D.C.



Temp. Range

5o - 60oC



Humidity

Up to 95% R.H.



Power Harmonics

Immune to any Harmonics











Thermal
Overload Relay

Electronic Relay
J & J - 7000



Overloading protection

Not
Adequate

Full protection against
overload is offered as per
inverse time-current
characteristic like
C.D.G.E./E.E. Overload
Relays that is higher the
current smaller the time to
trip matching thermal
endurance limits of motor
winding insulation



Single phasing protection

Nil

100%



Current unbalances & voltage
unbalance protection

Nil

100%



Protection against jamming
of Motor

Nil

100%



Bearing Failure Protection

Nil

100%



Misalignment Protection

Nil

100%



Fault Display

N.A.

Display faults reduces
machine detention



Energy efficiency

Inefficient

Efficient



Life expectancy

1-1.1/2 years

11 years



Facility of Remote Rest

N.A.

Yes



Store inventory

Yes

Nil



Harmonics

False Tripping

Immune to any harmonics



Overload tripping time

1-2 minute

2-10 seconds adjustable at site



Warranty

Nil

5 years



Normal Ageing of Motor
Insulation

Fast

Very slow ageing
enhancing operating life of
Motor





Visual Display of Faults Through LED




Auxiliary Supply ON

On

On



Auxiliary Supply OFF

Off

Off



Normal Healthy

On

On



Single/Reverse Phasing

Off

On



Reset Single/Reverse Phasing Trip

On

On



Over Load Trip

Off

On



Reset after Overload Trip

On

On