Instruction manual

Easy-Start ES Instruction Manual
The percent off-time is therefore 12/60 X 100 =
20%. We next look at the starts per hour Table
2-2 for a 70 amp starter (ES070). We can see
that the model ES070 can do only 40 starts per
hour at 350 amps with a start time of 5 seconds
and an off-time of 20%.
Therefore, we need to use the next larger size
starter, (ES120). From Table 2-3 we can see that
80 starts per hour are allowed at a starting
current of 360 amps with a start time of 5
seconds and a 20% off-time, by using the model
ES120.
Notice - The Easy-Start ES may trip due to
overcurrent, if repeated starts at high current and
long starting times, are used.
Starting Torque
The reduced voltage applied to the motor results
in reduced inrush current and soft start.
However, it reduces the starting torque of the
motor. The relationship is as follows:
Torque at Reduced
=
Current at Reduced
Current Voltage
2
Torque at Full Current Current at Full Voltage
EXAMPLE: A 100 HP 1800 RPM 460V NEMA B
motor draws six times full load amps for starting
and starting torque is 150% of full load torque.
If the same motor is started with Easy-Start ES at
300% current limit.
Starting Torque at 300% Current Limit = 300
2
600
x starting torque at 600% current = 1/4 x 150%
full load torque = 37.5% full load torque
Pre-Installation
INSTALLATION
2-8
Application Considerations
Frequent Starting/Stopping
The number of starts and stops depends upon
many factors. The most important ones are:
1. Position of current limit potentiometer which
can be anywhere from 200-500% of the
current rating set by the DIP switches.
2. Start time.
3. Run time.
4. Off time before next start.
The following tables (Table 2-1 thru Table 2-11)
can be used for guidance in frequent
starting/stopping application. These tables are
based on worst case condition that the controller
will be running at the indicated starting current
during the entire start time.
The number of starts-per-hour in the following
tables is based on the current carrying capacity
of the Easy-Start ES. If a high number of multiple
starts is used, the starter may trip due to the
inverse-time overload current protection function.
If a trip should occur, due to multiple starts, it is
advisable to wait a period of 10 minutes before re
starting to avoid damage to the Easy-Start ES.
Notice - The motor manufacturer should be
consulted about the effect of a high number of
multiple starts on motor life.
Zero % off-time in the starts per hour tables,
indicates jog duty.
EXAMPLE: If an application requires 1 start per
minute, 60 starts per hour, for a 460V, 50 HP, 70
Amp motor; the cycle time is 60 seconds
between starts. Assume a start time of 5
seconds, at a starting current of 500% (350
amps) is needed, with an off-time between run
and start of 12 seconds, and a run time of 43
seconds.
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