Grundfos CU 321 Installation And Operating Instructions página 23

Code LED Description
Overcurrent
The CU 321 peak current limit (approx. 200% of rated output current) has been exceeded.
The warning will last for approx. 1-2 seconds before the CU 321 is alarm-locked.
Check that the correct pump has been installed and that the CU 321 is programmed accord-
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ingly.
If OK, switch off the CU 321 power, disconnect motor leads and measure winding resistance,
looking for short-circuits between windings or ground.
If motor windings are OK, inspect pump and motor ensuring that both spin freely.
Ground fault
There is a discharge from the output phases to ground, either in the cable between the
14 CU 321 and the pump motor, or in the pump motor.
Switch off the CU 321 power, disconnect motor leads and measure winding resistance, look-
ing for short-circuits between windings or ground.
Internal fault
Internal fault in the CU 321 (internal supply). Contact your Grundfos supplier.
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Short-circuit
There is a short-circuit on the motor terminals of the CU 321 or in the pump motor.
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Switch off the CU 321 power, disconnect motor leads and measure winding resistance, look-
ing for short-circuits between windings or ground.
The CU 321 is not destroyed by a short-circuit.
Inrush fault
This alarm appears when line voltage has been applied to the CU 321 more than twice in one
35
minute.
Overtemperature
(internal temperature measurement)
The CU 321 gives a warning if the temperature inside the box goes too high. The motor con-
tinues to operate unchanged. The CU 321 will stop operating if the temperature continues to
rise.
The temperature fault cannot be reset until the temperature inside the CU 321 has dropped
below 158°F (70°C). The tolerance is ±9°F (±5°C).
The following can cause the temperature to rise:
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• Ambient temperature too high.
• Motor cable too long.
• AC line voltage too high.
• Dust covering the fan in the CU 321.
The CU 321 performance can be limited by reducing the max. speed in the installation menu.
The CU 321 will be able to operate with a slightly reduced performance at high ambient tem-
perature when the max. speed is reduced.
Internal fault
Internal fault in the CU 321. Contact your Grundfos supplier.
37-45
Dry run
The dry-run alarm shows that the well is dry or that the pump is too large for the well. If the
pump is too large for the well, it will be able to empty the well and a dry-run alarm will be gen-
erated.
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The dry-run alarm will reset in 30 minutes if automatic reset is selected.
If the power consumption is low and the pump speed is at maximum speed, a dry-run alarm is
generated.
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