ABB UMC100-FBP - Page 41

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Universal Motor Controller
UMC100-FBP
Technical Description
FieldBusPlug / Issue: 03.2012
Cyclic motor operation modes
Some applications require periodic start/operation/stop cycles. Setting up such applications requires care
when selecting the cooling down times or defining the shortest possible start period.
In the next diagram three successive start cycles are displayed. In each cycle the motor starts at 700% I
e
.
This high load lasts for about 7 seconds. Then the current goes back to I
e
within 6 seconds and stays at
100% I
e
for about 180 seconds. At T1 the motor is switched off and cools down for 200 seconds (cooling
time is set to 200s).
After the cooling time is over the next start takes place at T2. During this cycle the motor also cools down
for 200s but the calculated thermal motor load q is already above 40%. The third start at T4 leads - as
expected - to a thermal overload trip
For cyclic operation modes it is important to keep the cycles long enough to allow the
motor to cool down sufficiently.
For cyclic start patterns it is better to select the cooling mode option "Restart Level"
which allows a restart based on the thermal load level. In the case shown below the third
start would then be allowed at the earliest at T5 for the given q
R
.
θ
T
t[s]
T1
T2
T4
0
20
40
60
80
100
120
0 200 400 600 800 1000 1200 1400 1600
T3
θ
R
T5
 Trend of the calculated motor temperature after several starts. The motor trips after the third
start because the motor was started too frequently in the given time.
Relevant Parameters:
•Trip Class
•Set Current I
e1
and optionally I
e2
•Current Factor
•Cooling Mode
•Cooling Time
•Restart Level
•Thermal load Pre-Warning level
•Fault autoreset
q
T
: Thermal load
of the motor
q
R
: Configured
Restart Level
T
x
: Switching time
t: Time