Newelec KA Motor Protection Relay

Thermal Lock-out Period

In the event of an overload trip, the entire thermal capacity of the motor has been utilised. If auto reset has been selected, the motor overload LED will flash at a one-second rate, until the thermal capacity has integrated to 33%. At this point the overload LED will switch off. The relay healthy LED will switch on to indicate that the motor can be returned to service. The relay will reset to a class 5 hot Curve.

If manual reset is selected the motor overload LED will remain on until the control panel mounted reset button is pressed. If the thermal capacity has not integrated to 33% then the auto reset sequence is initiated. If the thermal capacity has integrated to > 33% then the overload LED will switch off. The relay healthy LED will switch on to indicate that the motor can be returned to service.

Unbalance / Single phasing

Phase unbalance protection is provided independent of motor load. In the event of the three line currents becoming unbalanced by more than 30% a 5 second trip delay is initiated.

Phase Rotation

Incorrect phase rotation will result in the phase rotation LED switching on. The relay healthy LED will then switch off and de-energise the main trip relay. This will prevent motor operation with incorrect phase sequence and resultant damage to driven equipment. Once the phase rotation has been corrected the phase rotation LED will switch off and re-energise the main trip relay. The relay healthy LED will then switch on to indicate that the motor can be returned to service.

Phase Symmetry

In the event of the phase voltages becoming unbalanced by more than 10% a 2 second trip delay is initiated after which the phase rotation LED is pulsed at a one second interval. The relay healthy LED will then switch off and trip the main relay. If the unbalance level reduces to below 10% then the flashing phase rotation LED will switch off and re-energise the main trip relay. The relay healthy LED will then switch on to indicate that the motor can be returned to service.

Overvoltage

In the event of the main circuit voltage becoming greater than 115 % of rated supply a two second trip delay is initiated. After this the phase rotation LED is pulsed at a 75% duty for a 4 second period. The relay healthy LED will then switch off and de-energise the main trip relay. If the main circuit voltage level reduces to below 115% then the flashing phase rotation LED will switch off and re-energise the main trip relay. The relay healthy LED will then switch on to indicate that the motor can be returned to service.

Undervoltage

In the event of the main circuit voltage becoming less than 90% of rated supply a two-second trip delay is initiated. After this the phase rotation LED is pulsed at a 25% duty for a 4 second period. The relay healthy LED will then switch off and de-energise the main trip relay. If the main circuit voltage level increases to above 90% then the flashing phase rotation LED will switch off and re-energise the main trip relay. Tile relay healthy LED will then switch on to indicate that the motor can be returned to service.

Under current Protection

The minimum load current level adjustment range is 10% to 100% of the rnax load current dial setting. If the load current drops below the set value but is > 10% of motor Ifl a 25 second trip delay is initiated. If the load current does not increase above the under current level adjustment or drop below 10% of motor full load current setting within 25 seconds the motor will be tripped on undercurrent.

Should the load current increase above the under current level setting the under current trip timer is reset and will start a fresh trip timing cycle on the next undercurrent condition. The undercurrent condition must persist for an uninterrupted 25 second period to effect an undercurrent trip. Any recovery within the 25 second period will result in the re initialisation of a new 25 second trip period.

LED Indication

Red LED trip indicators with clear descriptive fault conditions have been mounted oil the control panel to assist maintenance personnel in determining the exact cause of a trip.

Motor Overload

This indicator will be illuminated and the main trip relay operated if the motor load has exceeded the thermal capacity allowed by the thermal IDMT curve (class 15 cold and class 5 hot curve). Should the control panel mounted reset pushbutton be pressed in this state, or if the auto manual reset slide switch is set to auto, the motor overload LED will start to flash at a 50% duty for a 1 second period until the thermal capacity value recovers to 33%. At this point the main trip relay will re-energise and the relay healthy LED will switch on to indicate that that the motor can he returned to service. An additional function of the motor overload LED for maintenance or commissioning personnel is the ability to read the actual load cur-rent being drawn by the motor. This is achieved by holding the reset push button and trimming back the maximum load current dial until the motor overload LED switches on. The calibration on the max load current dial at which this occurs is the actual load current being drawn by the motor.

Phase Unbalance

This indicator will be illuminated when the three line currents drawn by the motor become unbalanced by more than 30% after which a 5 second trip delay is initiated.

Min Load Trip

The min load indicator will switch on and the main trip relay will de-energise 25 seconds after a min load condition when the motor load current drops below the min load % MLC dial setting, but is >10% of the max load current dial value and remains in this state for the full 25 second period. If during this 25 second period the load current increases above min load % MLC dial setting and then drops below this value once more a new 25 sec trip delay period is initiated.

Phase Rotation

This indicator is used to indicate various Supply voltage related problems as follows:

Unbalance/Single Phasing Sensor
    Maximum Level Setting          > 30% I.e. (motor full load)
    Trip Delay                             5 seconds

Overload Trip Delay Curves
    COLD
    Ttrip = 15 (35,49 x heat^ln (I/Ie)^ 2 / (I/Ie)^2 - 1)

    HOT
    Ttrip = 5 (35,49 x heat^ln(I/Ie)^2 / (I/Ie)^2 - 1)
    Accuracy    + 5%
        1,2 I.e. to 10 I.e.
        + 10%
        1,01 I.e. to 1,2 I.e.

Overload Thermal Lock-out Time to recover 33 % Capacity
Treset = Curve [2,33 (35,49 x 2) 15 log (100 / 70)] - Motor running

Treset = Curve [2,33 (35,49 x 4) 15 log (100 / 70)] - Motor standstill

Overload	Cyclic and sustained overload with pre loading, thermal memory, hot and cold curve
Unbalance/Single Phasing	Motor load currents unbalanced > 30% on starting, running or light loads.
Phase Rotation	Prevents motor operation with incorrect supply voltage phase sequence.
Phase Symmetry	Prevents motor operation with supply voltage phase unbalance > 5%.
Overvoltage	Prevents motor operation when main circuit voltage is > 1 15% of rated supply.
Undervoltage	Prevents motor operation when main circuit supply voltage is < 90% of rated supply.
Minimum Load	Minimum load trip level adjustable from 10% to 100% motor Ifl with a 25 second trip delay.

Fault	Indication pattern
Incorrect Phase Rotation	LED switches on and stays on. Remove supply, correct and restore to reset.
Unbalanced voltage	LED switches on and off at 1sec rate. Resets when supply unbalance <10%
Supply Overvoltage	LED switches on 3 sec off for 1 sec. Resets when supply voltage <115%Vs
Supply Undervoltage	LED switches on 1 sec off for 3 sec. Resets when supply voltage >90%Vs

Model	Setting Range	Max Reading	CT Ratio (External)
KA 10	1 to 10 amps	50 amps	Direct
KA 25	2,5 to 25 amps	250 amps	Direct
KA 50	5 to 50 amps	500 amps	50 to 5
KA 100	10 to 100 amps	500 amps	100 to 5
KA 200	20 to 200 amps	2000 amps	200 to 5

Input Converter (Internal)		Maximum Load Current Sensor
Current Transformer Ratio	1 000: 1	Level Setting Accuracy	+/- 4%
CT Secondary	1 amp	Linearity	+/- 4%
Class	Class 1	Repeatability	+/- 1%
Rating	0.1 va	Detection Level	+/- 1%
Frequency Response	40 - 66 Hz	Calibration	arnps

Model	Min	Max
KA 10	1	10
KA 25	2,5	25
KA 50	5	50
KA 100	10	100
KA 200	20	200


	Wiring diagram. Panel installation by Woodrow Engineering, (Kimberley)cc.