Edwards nEXT730D User Manual

7.8.3 Protecon ag
ainst over-speed
Control soware within the motor controller regulates the pump rotaonal speed and
prevents the pump operang above its normal full rotaonal speed.
In the unlikely event of a failure of this control soware, the motor controller has a built-
in safety circuit that checks whether the pump is running at over-speed. If an over-speed
condion is detected, the motor controller automacally shuts down power to the
pump motor and slows it down to rest. The motor controller will signal a fail condion if
over‑speed has been detected.
If the pump appears to be running at over-speed, switch it o and consult Edwards or
the supplier.
7.8.4 Electrical supply failure
If the electrical supply to the nEXT pump fails when the pump is rotang, the pump
motor is used as a generator.
WARNING:
If the pow
er supply fails when the pump is running, the rotor could connue to spin
for approximately 30 minutes. The control circuit may not give any indicaon that the
rotor is sll running.
CAUTION:
If the parallel s
tart control signal on the logic interface connector is set to start, the
pump may automacally restart when the electrical supply is restored aer an
electrical supply failure. Ensure that people cannot be injured by the rotang blades
of the pump.
The regenerated power is used to maintain the output signals on the logic interface
(such as the normal signal and serial communicaons), to power the indicator LEDs on
the motor controller and to maintain power at the motor controller auxiliary outputs (to
control the vent valve and/or fan, if ed). The regenerated power is also available at
the power supply interface connector, but only when electronic braking is enabled (refer
to Electronic braking on page 17). This could be used to power other instruments
through short power interrupons. The minimum voltage of this supply will be 48 V d.c.
- 15 % (40.8 V) provided that the external load is not excessive and it can be sustained at
that minimum voltage when operang from supply voltages above 48 V d.c. -20% and
below 48 V d.c. +5%.
As the pump rotaonal speed decreases, the motor's ability to generate power also
decreases unl it is no longer able to maintain power to the logic interface or LEDs. This
will occur at speeds below 50% full rotaonal speed. In this case, there will be no
indicaon of pump rotaonal speed yet the rotor may sll be turning.
When the power is reinstated aer a power failure, the behaviour of the pump will
depend on the control mode at the me of failure (parallel or serial) and the length of
me the pump was without power. Table: Behaviour of a pump when the power is re-
instated aer an electrical supply failure shows a number of scenarios.
08/2021 - ©Edwards Limited
Page 86B8J200880_D
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B8J200880_D - Operaon

Edwards nEXT730D Specifications

General

Brand	Edwards
Model	nEXT730D
Category	Water Pump
Language	English