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Electrical Test lnstruments MAC-20 Retrofit Package

Section ll

Detailed Description

ASCII format to a

printer

or other device.

LATCH key: This key toggles

the

LATCH mode

for initiation; its LED indicates that this

mode is enabled. When in LATCH mode, the INITIATE key need only be

pressed

briefly to turn output on. LATCH must be set in order to

read

pulse

current

when output

is initiated by means other than the MAC-20.

N.O. key: This key is used to set the Normally Open contacts mode. ln this mode, lack

of continuity on the CONTACTS binding

posts

indicates that the

protective

device under

test

is in its normal

(non{ripped)

mode, and ready to accept current.

This mode may

also

be selected to use

the

MAC-20

as a

manually

operated

timer. ln N.O. mode,

ihe

timer starts as soon as the INITIATE key is

pressed,

and stops when released

(if

not in

LATCH mode), or when the STOP key is

pressed

or continuity is sensed at the

CONTACTS

binding

posts.

Timing accuracy in this mode is typically

+l-

0.01 seconds.

N.C. key:

This key is

used to set the

Normally

Closed

contacts mode. ln this mode,

continuity

on the CONTACTS binding

posts

indicates that the

protective

device under

test is in its normal

(non-tripped)

mode,

and

ready

accept current. This mode may be

used

for

testing

multi-pole breakers by connecting the CONTACTS binding

posts

to an

unused

pole.

ln N.C. mode, the timer starts as

soon as the INITIATE key is

pressed,

and

stops

when

released

(if

not in LATCH mode), or when the STOP key is

pressed

a break in continuity

sensed

at the CONTACTS binding

posts.

Timing accuracy in this

mode is typically

+/-

0.01

seconds.

C.L. key combination:

When the N.O. and N.C. keys are

pressed

simultaneously,

both

LEDs

light, indicating

C.L.

mode

(Cunent

Latch).

This is the normal

power-up

default

mode for the test set, and

is recommended for all tests, unless there

good

reason

for

using

contacts to sense trip. ln this

mode, current is continuously sampled, and

when it exceeds approximately

10% of the maximum current range

value,

the timer

starts,

and calculation of

pulse

current

begins. When current stops

(or

drops

below a

dynamically determined

threshold value), the timer stops

running, and the final

value

for

pulse

current

is calculated and displayed.

lf the output was initiated by the

MAC-20, it is

turned OFF.

PRESET

key: This key toggles the

PRESET ADJUST

mode, indicated by illumination

its

LED.

When PRESET

ADJUST is active, the adjacent

SECONDS and CYCLES

keys

respectively lower and

raise the

preset

time

in seconds or cycles, depending on

the timebase

that was selected.

Both

keys may be

pressed

simultaneously

to reset the

time limit to zero,

which disables the

time limit function. When

not in PRESET mode,

the

LED will

flash if the displayed

time exceeds the

preset

limit.

SECONDS

key: This key

normally selects the SECONDS

timebase. lf the

PRESET

mode

is selected, this

key is used to

LOWER the

preset

time

limit

by 0.100

second

increments

with the SECONDS

timebase, or 0.5

cycle increments with the CYCLES

timebase.

lf it is held, the

reading will decrease at

a rate of about 5

intervals

per

second.

lf a

preset

time

limit was set

in SECONDS mode, the

output will be turned off

within several milliseconds

after the

limit has been reached. SECONDS

or CYCLES

Electrical

Test lnstruments. lnc.

Page

ll-5

1 994-1998

Brand	Electrical Test Instruments
Model	MAC-20
Category	Controller
Language	English

Electrical Test Instruments MAC-20 User Manual

Table of Contents

Questions and Answers:

Electrical Test Instruments MAC-20 Specifications