Abbreviations are frequently used in control circuits. The following list identifies a few commonly used abbreviations: –

MTR Motor
MN Manual
NEG Negative
NEUT Neutral
NC Normally Closed
NO Normally Open
OHM Ohmmeter
OL Overload
PB Pushbutton
PH Phase
POS Positive
PRI Primary
PS Pressure Switch
R Reverse
REC Rectifier
RES Resistor
RH Rheostat
S Switch
SEC Secondary
SOL Solenoid
SP Single-Pole
SPDT Single-Pole, DoubleThrow
SPST Single-Pole, SingleThrow
SS Selector Switch
SSW Safety Switch
T Transformer
TB Terminal Board
TD Time Delay
THS Thermostat Switch
TR Time Delay Relay
U Up
UV UnderVoltage
VFD Variable Frequency Drive
XFR Transformer
AC Alternating Current
ALM Alarm
AM Ammeter
ARM Armature
AU Automatic
BAT Battery
BR Brake Relay
CAP Capacitor
CB Circuit Breaker
CKT Circuit
CONT Control
CR Control Relay
CT CurrentTransformer
D Down
DC Direct Current
DISC Disconnect Switch
DP Double-Pole
DPDT Double-Pole, Double-Throw
DPST Double-Pole, Single-Throw
DT DoubleThrow
F Forward
FREQ Frequency
FTS Foot Switch
FU Fuse
GEN Generator
GRD Ground
HOA Hand/Off/Auto Selector Switch
IC Integrated Circuit
INTLK Interlock
IOL Instanstaneous Overload
JB Junction Box
LS Limit Switch
LT Lamp
M Motor Starter

 

AUTHORS
1.Bunty B. Bommera
2.Dakshata U. Kamble

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