Instruction manual

10-14
(5) Any other loads connected
to the same power supply
has required a large starting
current, causing a
temporary voltage drop.
Measure the input voltage and check the voltage fluctuation.
 Reconsider the power supply system configuration.
(6) Inverter's inrush current
caused the power voltage
drop because the power
supply transformer capacity
was insufficient.
Check if the alarm occurs when a molded case circuit breaker (MCCB),
residual-current-operated protective device (RCD)/earth leakage circuit breaker
(ELCB) (with overcurrent protection) or magnetic contactor (MC) is turned ON.
Reconsider the capacity of the power supply transformer.
[ 5 ] Input phase loss
Problem Input phase loss occurred, or interphase voltage unbalance rate was large.
Possible Causes
What to Check and Suggested Measures
(1) Breaks in wiring to the main
power input terminals.
Measure the input voltage.
 Repair or replace the main circuit power input wires or input devices (MCCB,
MC, etc.).
(2) The screws on the main
power input terminals are
loosely tightened.
Check if the screws on the main power input terminals have become loose.
 Tighten the terminal screws to the recommended torque.
(3) Interphase voltage
unbalance between three
phases was too large.
Measure the input voltage.
 Connect an AC reactor (ACR) to lower the voltage unbalance between input
phases.
 Increase the inverter capacity.
(4) Overload cyclically
occurred.
Measure the ripple wave of the DC link bus voltage.
 If the ripple is large, increase the inverter capacity.
(5) Single-phase voltage was
input to the three-phase
input inverter.
Check the inverter settings and service condition.
 Correct them for single-phase use, referring to Chapter 1, Section 1.3.4
"Precautions for use on single-phase input.
(6) Running on single-phase
power
 Refer to Section 10.7 "If the Inverter is Running on Single-Phase Power,"
[ 5 ].
The input phase loss protection can be disabled with the function code H98 (Protection/Maintenance Function).
[ 6 ] Output phase loss
Problem Output phase loss occurred.
Possible Causes
What to Check and Suggested Measures
(1) Inverter output wires are
broken.
Measure the output current.
 Replace the output wires.
(2) The motor winding is
broken.
Measure the output current.
 Replace the motor.
(3) The terminal screws for
inverter output were not tight
enough.
Check if any screws on the inverter output terminals have become loose.
 Tighten the terminal screws to the recommended torque.
(4) A single-phase motor has
been connected.
 Single-phase motors cannot be used. Note that the EQ7 only drives
three-phase induction motors.