"VR" voltage relays are used for reversing-plugging
controllers with Emergency or Service Dynamic Braking, and for armature
shunt contactors on multi-step slowdown circuits.
"JK" voltage relays are used for
initiating high speed lowering on hoist controllers.
"LSR" is a Limit Switch Relay standard for
hoist control panels with power limit switch.
"NP" is a Non-Plugging Relay for compound and shunt motors.
"PR" Plugging Relays are rectifier type used
on dc reversing plugging control panels to limit motor torque during plugging operations.