M

MAKE AND BREAK
Make and break are terms which apply to any switching situation, but particularly to Intermittent Duty Solenoids, where the buildup of heat can cause failure of the component.

Make and break are RATINGS. A particular component, such as a solenoid, may be rated for duty at a given amperage and voltage that should not be exceeded.

Make is when the switch (or solenoid) is turned On (the circuit is 'made'), and break is when the switch is turned Off (the circuit is 'broken'). Such values would need to be checked with an instrument such as a meter.

Note also that Intermittent Duty Solenoids have a limitation on the time (duty cycle) they may be kept On and the time they need to recover (to allow heat dissipation.)

MASTER DISCONNECT SWITCH
A master switch that disconnects a battery from the load. This provides a good measure of safety and security. Installation of such a switch is often mandatory to allow safe servicing operations. See the Cole Hersee catalog for a broad range of switches with ratings up to 2000A. More info: CF-100

MEGA M
A metric prefix meaning a magnitude of 1,000,000 or 10^6. See Metric Prefixes

METER or METRE m
The meter is the basic unit of length. It is the distance light travels in a vacuum in 1/299792458th of a second.

METRIC PREFIXES
The Systeme International allows the sizes of units to be made bigger or smaller by the use of appropriate prefixes.

For example, the electrical unit of a watt is not a big unit even in terms of ordinary household use, so it is generally used in terms of 1000 watts at a time. The prefix for 1000 is kilo so we use kilowatts [kW] as our unit of measurement. For makers of electricity, or bigger users such as industry, it is common to use megawatts [MW] or even gigawatts [GW].

yotta Y
1 000 000 000 000 000 000 000 000 10^24

zetta Z
1 000 000 000 000 000 000 000 10^21

exa E
1 000 000 000 000 000 000 10^18

peta P
1 000 000 000 000 000 10^15

tera T
1 000 000 000 000 10^12

giga G
1 000 000 000 a billion

mega M
1 000 000 a million

kilo k 1 000 a thousand

hecto h 100

deca da 10

1

deci d 0.1

centi c 0.01

milli m 0.001 a thousandth

micro µ 0.000 001 a millionth

nano n 0.000 000 001 a thousand millionth

pico p 0.000 000 000 001 10^-12

femto f 0.000 000 000 000 001 10^-15

atto a 0.000 000 000 000 000 001 10^-18

zepto z
0.000 000 000 000 000 000 001 10^-21

yocto y
0.000 000 000 000 000 000 000 001 10^-24

[µ] the symbol used for micro is the Greek letter mu.
Nearly all of the SI prefixes are multiples or sub-multiples of 1000. However, these are inconvenient for many purposes and so hecto, deca, deci, and centi are also used. deca also appears as deka [da] or [dk] in the USA and Continental Europe.

MIL
A unit of length equal to one-thousandth, 10^-3 of an inch.

MICRO µ
A metric prefix meaning one millionth of a unit or 10^-6. See Metric Prefixes

MICRON
A metric term meaning one millionth of a meter.

MILLI m
A metric prefix meaning one thousandth of a unit or 10^-3.

MOMENTARY (often abbreviated to 'mom')
A type of spring-loaded switch, that when actuated, returns to its original position (usually Off, but we make switches that return to On).

At Cole Hersee, we make lots of momentary switches in different types (Push switches, ignition switches, toggle switches, rocker switches, rotary switches). You have lots to choose from.

Momentary switches are useful in situations where you need a short time actuation. Examples would be in the 'push-to-wash' of a windshield wiper switch, or a starter button.

MTBF (Mean Time Between Failure)
The probable length of time that a component taken from a particular batch will survive if operated under the same conditions as a sample from the same batch.
An important engineering concept that is employed at Cole Hersee to ensure reliability of switches.