Flowserve PLEUGER - Manual (Page 20)

PLEUGER STANDARD USER INSTRUCTIONS ENGLISH 71569293 01-13
Page 20 of 40 flowserve.com
5.6 Adjustments for soft-starter and soft
stop devices
5.6.1 Minimum permissible current limits
Table 5-2
Motor type
Minimum permitted current limit as
% of motor rated current
M6 250
M8 up to VNI 14 300
MI 16 350
> MI 16 On request
5.6.2 Minimum start-up voltage
On adjustable devices do not adjust the start-up
voltage lower than 55 % of the rated voltage.
5.6.3 Permissible ramp-up time
To avoid thermal overload and damage to the bearings
DO NOT adjust the ramp-up time above 5 seconds.
On units with a dual ramp-time function or pump
function the sum of the dual ramp-time must not
exceed 5 seconds. Any other ramp-up time above 5
seconds must be referred to Flowserve for approval.
Should external guidelines state differing values than
those stated above, the above values must take
precedent. This function should not be used for
speed adjustment of the motor.
5.6.4 Permissible ramp-down time
The maximum ramp-down time must not exceed 20
seconds.
On units with a dual ramp-time-function or pump-
function the total amount of ramp-time must not exceed
20 seconds. The amount of running-out voltage in this
case must not be less than 45 % of the rated voltage.
Any other ramp-down time above 20 seconds must
be referred to Flowserve for approval.
Should external guidelines state differing values than
those stated above, the above values must take
precedent. This function should not be used for
speed adjustment of the motor.
5.6.5 Starting frequency
Table 5-3
Motor type Maximum starts and run-outs per hour
M6 8
M8 to MI16 6
> MI16 On request
The number of starts per hour should be spread
equally over the hour.
In addition, pay attention to the starting frequency of
the soft-start device, which could possibly be less.
5.6.6 Soft starter current limit
To have sufficient reserve for any required additional
acceleration torque, the choice of the soft-start device
must be carefully considered to ensure that the
starter can deliver at least four times the motor rated
current.
5.7 Operation of submersible motors
with static frequency converter
5.7.1 General
Motors for operation with a static frequency converter
are specially designed. Major operating criteria are
the temperature rise of the motor depending on
additional losses and the higher voltage stress on
static frequency converter operation.
5.7.2 Cooling
Generally, the flow velocity along the motor must be
guaranteed for the nominal condition according to
table 5-4.
Table 5-4
Ambient temperature Minimum flow velocity
30 °C (86 °F) 0.5 m/s (1.64 ft/sec)
20 °C (68 °F) 0.2 m/s (0.66 ft/sec)
5.7.3 Starting conditions
The minimum frequency of 10 Hz must be reached
within 0.5 seconds.
5.7.4 Permissible operating frequency range
The acceptable operating frequency is from a
minimum of 10 Hz up to a maximum of the nominal
frequency. (Refer to the data card.)
In this case the allowable pumping
capacity range must be observed. (See section
3.3.1, Normal operating conditions.) This may result
in a minimum operating frequency above 10 Hz.
5.7.5 Maximum voltage stress
The rise in voltage should be less than 500 V/µs and
be limited to 1.5 U
N
.
5.7.6 Power cable
Shielded power cables should be used at the top of the
borehole/well. The cables between the submersible
motor and the surface connections must be installed in
an adequate Cu-mesh shield that is extensively earthed
on both sides.