Toshiba Current Relay RC803A-HP1 - Manual (Page 17)

(6) If the relay does not operate in the above test, check if
the current setting is correct or if the signal is
above the set detection value. If the signal is
correct, check the operation of the relay by gradually
reducing the setting of the current adjusting knob. If the
relay still does not it is defective. In this case,
please contact the dealer which you purchased the relay
or Toshiba.
Power Source
Detected current
Overcurrent
detect ion
Undercurrant
T3
detect ion
I
Detection delay tire
T2: Overcurrent detecting resgonse delay
T3: Undercurrent detecting resgonse delay
Fig. Relay Operation