WEG SSW-06 User Manual

CHAPTER 7 - PROGRAMMING INFORMATION AND SUGGESTIONS
160
7.2.1.3 Time Reduction When
Changing from Cold
Starting to Hot Starting
7.2.1.4 Service Factor
Figure 7.26 - Using the S.F. to nd new times
t(s)
0
xIn
of the Motor
15
20
25
Cold
S.F.=1.15
S.F.=1.25
2x
3x
4x
2)Inthechart,athotinP640,wecanndthemaximumThermalClass
that the motor will withstand due to the locked rotor time at hot:
For 6.6 x In @ 12s, we select the closest lower Class: Class 40.
Now it is known that Thermal Class 10 allows one start and Thermal
Class 40 is the upper limit. Thus you must select a Thermal Class
between these two Thermal Classes by considering the number of
startsperhourandthetimeintervalbetweenmotorO󰀨-Onprocedures.
The closer to Class 10 you select, more protected will be your motor,
less starts per hour are allowed and longer time intervals between
motorO󰀨-Onproceduresarerequired.
The closer to Class 40 you select, you will be nearer the upper motor
limit, thus more starts per hour are allowed and shorter time intervals
betweenmotorO󰀨-Onprocedurescanbeused.
To determine the activation times of the hot Thermal Classes, when the
motor is running at rated load with current lower than 100% of the In,
use the multiplier factor shown in table 6.46 at P640, as a percentage
of the current that the motor is absorbing when running continuously.
For example:
Amotorisrunningwith80%InandthenisswitchedO󰀨.
It is switched On again immediately.
The starting current is 3xIn @ 25s.
The selected Thermal Class, in the table 6.43, is the Class 10 with
33.7s @ 3xIn.
As shown in table 6.46, the correction factor for 80% In is 0.48.
Thenalactivationtimewillbe:0.48x33.7s=16.2s,and,thetime
is reduced at cold start from 33.7s to 16.2s at hot start. Thus, a new
motor start is not allowed before the thermal motor image decreases,
the motor cools down.
WhentheServicefactor(S.F.)isdi󰀨erentfrom1.00,butitsuseis
required,youcanndinthechart,at cold, the points for the S.F. =
1.15 and a table for S.F. = 1.15, see P640.
If you want to know the thermal protection activation time for other
Service Factor (S.F.), displace the line xIn proportionally to the left.

WEG SSW-06 Specifications

General

Brand	WEG
Model	SSW-06
Category	Controller
Language	English