Cyclic Motor Operation Modes; Relevant Parameters - ABB UMC100.3 Manual

U M C 1 0 0 . 3 U N I V E R S A L M O T O R C O N T R O L L E R T E C H N I C A L D E S C R I P T I O N
40

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% Ie. This high load lasts for about 7 seconds. Then the current goes back to Ie within 6 se-
conds and stays at 100% Ie for about 180 seconds. At T1 the motor is switched off and cools down for 200 seconds (cooling time is
set to 200 s). After the cooling time is over the next start takes place at T2. During this cycle the motor also cools down for 200 s
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 suffici-
ently. 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
θ
T
120
100
80
60
40
θ
R
20
0
0 200 400
T1
T2
—
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 and optionally I
e1
• Current Factor
• Cooling Mode
.
R
600 800 1000
T3 T4
• Cooling Time
• Restart Level
e2
• Thermal load Pre-Warning level
• Fault autoreset
1200 1400 1600
T5
q
: Thermal load of the motor
T
q
: Configured Restart Level
R
T : Switching time
x
t: Time
t[s]