38
The frequency of starts is usually determined by the maximum temperature increase of the
motor. This largely depends on the power reserves of the motor in steady- state operation
and on the starting conditions (d.o.l., star-delta, moments of inertia, etc). If the start-ups are
evenly spaced over the period indicated, the following limits can be used for orientation for
start-up with the discharge-side gate valve slightly open:
6.2.1 Ambient temperature
6.2.2 Frequency of starts
Table 17: Frequency of starts
Observe the following parameters and values during operation:
Table 16: Permissible ambient temperatures
6.2.3 Flow rate
Unless specified otherwise in the characteristic curves or in the data sheets, the following
applies:
. Short-time operation: Q
min
8)
=0.1xQ
opt
9)
. Continuous operation: Q
min
8)
=0.3xQ
opt
9)
2-pole operation: Q
max
10)
=1.1xQ
opt
9)
4-pole operation: Q
max
10)
=1.25xQ
opt
9)
The data refer to water and water-like fluids. Longer operating periods with these fluids and
at the flow rates indicated will not cause an additional increase in the
C AUTION
Operation outside the permissible ambient temperature
Damage to the pump (set)!
Observe the specified limits for permissible ambient temperatures.
Value
Maximum
40 °C
Minimum
See data sheet.
Permissible ambient temperatures
DANG E R
Excessive surface temperature of the motor
Explosion hazard!
Damage to the motor!
In case of explosion-proof motors, observe the frequency of starts specified in
the manufacturer's product literature.
M otor rating
[kW ]
M aximum number of start-ups
[Start-ups/hour]
up to 12
15
up to 100
10
more than 100
5
C AUTION
Re-start while motor is still running down
Damage to the pump (set)!
Do not re-start the pump set before the pump rotor has come to a standstill.
8) Minimum permissible flow rate
9) Best efficiency point
10) Maximum permissible flow rate
6 Commissioning/Start-up/Shutdown
