A07520 — Drive: Motor cannot be changed over

A07520 is an alarm that the drive raises when a motor changeover cannot be carried out. In this function the drive switches between motors through contactors, and one of the conditions for the changeover is not met. The G130/G150 and S120/S150 manuals describe the alarm with identical causes and remedies. The drive stores an alarm value in r2124; interpreted as a decimal number it shows which of three situations stopped the changeover (see the alarm value list below).

• Alarm value 1: the contactor for the presently active motor cannot be opened. With a synchronous motor this happens while the speed r0063 is greater than the speed at the start of field weakening p0348: as long as r0063 > p0348, the current in the motor does not decay in spite of the pulses being suppressed.
• Alarm value 2: the 'contactor opened' feedback signal was not detected within 1 s.
• Alarm value 3: the 'contactor closed' feedback signal was not detected within 1 s.

1. Read the alarm value in r2124 and interpret it as a decimal number — it tells you which of the three situations applies.
2. Alarm value 1 — reduce the speed: Set the speed lower than the speed at the start of field weakening (r0063 < p0348).
3. Alarm values 2 and 3 — check the feedback signals of the contactor involved: the 'contactor opened' signal for alarm value 2, the 'contactor closed' signal for alarm value 3.

• The drive writes the alarm value into r2124 and it must be interpreted as a decimal number; this alarm value appears as the message value %1.
• 1 — the contactor for the presently active motor cannot be opened, because for a synchronous motor the speed r0063 is greater than the speed at the start of field weakening p0348; as long as r0063 > p0348, the current in the motor does not decay in spite of the pulses being suppressed.
• 2 — the 'contactor opened' feedback signal was not detected within 1 s.
• 3 — the 'contactor closed' feedback signal was not detected within 1 s.

• r2124 — alarm value: read it as a decimal number to identify which of the three causes (1, 2 or 3) the drive has detected.
• r0063 — CO: Actual velocity smoothed: the smoothed actual speed that, at alarm value 1, is compared with p0348.
• p0348 — the speed at the start of field weakening: the threshold of alarm value 1; the changeover contactor cannot be opened while r0063 > p0348, and the remedy requires r0063 < p0348.

A07520 does not trip the drive and requires no acknowledgement: the alarm clears by itself once the changeover can be completed again — at alarm value 1 when the speed has been set so that r0063 < p0348, at alarm values 2 and 3 when the contactor feedback signals are detected again. No restart is needed.