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GE Power Management MDP Digital Time Overcurrent Relay 2

GEK-100682D 2 OPERATING PRINCIPLES

2.8 SETTINGS

a) PICKUP TOC

The pickup is the sum of the switches in the right-hand position, plus the base pickup. For example, if the sec-

ond, third, and fifth phase TOC switches are in the right-hand position, the pickup current on a 5 A rated relay

would be:

b) PICKUP IOC

The IOC pickup is the sum of the switches in the right-hand position

times the TOC pickup

. For example, if the

second and third switches are in the right-hand position, the IOC pickup would be 2 + 4 = 6 times the TOC set-

ting. Using the 9.75 A set above, this would result in an IOC pickup of 58.5 A.

c) TIME DIAL

The time dial is the sum of the switches in the right hand position plus the base 0.05 or 0.5. The time dial cali-

bration is 0.05 for 1 A rated relays and 0.5 for 5 A rated relays.

d) CURVE SELECTION

Eight curves can be selected by means of the three curve selection switches. The settings are as follows:

The time delay of the definite time curve is the range times the time dial for 1 A relays and the range times the

time dial divided by 10 for 5 A relays. For example, to obtain a 3 second operating time, the time dial would be

set first, third, and fourth switches to the right and second and fifth switches to the left, that is:

The 6 second curve would be chosen with the curve switches left, left, and right. The time delay is 6 (curve)

times 0.5 (time dial) = 3 seconds for 1 A relays. For 5 A relays, the time dial (5) is divided by 10, also resulting

in a 3 second delay.

CURVE FIRST (TOP) SECOND (MIDDLE) THIRD (BOTTOM)

Inverse / (BS142) Inverse

1. For 1 A models, the inverse curve is defined by BS142

right right right

Very Inverse right right left

Long Time Inverse right left left

Extremely Inverse right left right

2 Second Definite left right right

4 Second Definite left right left

6 Second Definite left left right

8 Second Definite left left left

base of 1.5 0.75 1.5 6 A+++ 9.75 A=

Time Dial base of 0.05 0.05 0.2 0.2 A+++ 0.5 A [1 A]==

Time Dial base of 0.5 0.5 2 2 A+++ 5 A [5 A]==

Courtesy of NationalSwitchgear.com

GE MDP User Manual

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