Motor Stall Protection; Underload (Dry Pump) Protection - Vacon 100 flow Applications Manual

Monitoring value and parameter descriptions
8.9.2

Motor stall protection

The motor stall protection protects the motor from short time overload situations such as one
caused by a stalled shaft. The reaction time of the stall protection can be set shorter than that of
motor thermal protection. The stall state is defined with two parameters, P3.9.3.2 (
Stall frequency limit
and P3.9.3.4 (
frequency is lower than the set limit the stall state is true. There is actually no real indication of the
shaft rotation. Stall protection is a type of overcurrent protection.
NOTE! If you use long motor cables (max. 100m) together with small drives (≤1 .5 kW), the motor
current measured by the drive can be much higher than the actual motor current due to capacitive
currents in the motor cable. Consider this when setting up the stall protection functions.
P3.9.3.2 S
TALL CURRENT
The current can be set to 0.0...2*IL. For a stall stage to occur, the current must have exceeded
this limit. If parameter P3.1.3.1
calculated to 90% of the current limit.
NOTE! In order to guarantee desired operation, this limit must be set below the current limit.
Figure 80. Stall characteristics settings, ID 710 = P3.9.3.2 Stall current, ID 712 = P3.9.3.4 Stall
P3.9.3.3 S
TALL TIME LIMIT
This time can be set between 1.0 and 120.0 s.
This is the maximum time allowed for a stall stage. The stall time is counted by an internal up/down
counter.
If the stall time counter value goes above this limit the protection will cause a trip (see P3.9.3.1).
8.9.3

underload (dry pump) protection

The purpose of the motor underload protection is to make sure that there is load on the motor when
the drive is running. If the motor loses its load there might be a problem in the process, e.g. a
broken belt or a dry pump.
Motor underload protection can be adjusted by setting the underload curve with parameters
Underload protection: Field weakening area load
P3.9.4.2 (
24-hour support +358 (0)201 212 575 • Email: vacon@vacon.com
). If the current is higher than the set limit and the output
(ID 710)
Motor current limit
I
Stall area
Par. ID710
frequency limit
(ID 711)
is changed, this parameter is automatically
9130.emf
f
Par. ID712
Zero frequency load
) and P3.9.4.3 (
vacon • 199
Stall current
)
).
8