MICROENER MM30-D - Functions and Settings; Thermal Image Function (F49); Motor Protection Settings

MM30-D
Doc. N° MO-0037-ING
Rev. 4
Date 24.02.2003
Copyright 2010 - Microener
Pag
7
of
36
2.2.3 – Functions and Settings
2.2.3.1 – F49 – Thermal Image (See curves § 19)
The current “ I “ producing motor warming-up is computed as a conventional composition of
Positive Sequence “ Id “ and Negative Sequence “ Is “ components of the motor current.
- Computed current:
- Allowed overloading time (See Curve § 19)
The trip time delay “ t “ of the thermal element, depends on the warming-up time constant
“ tm “ of the motor, on the previous thermal status (Ip), on the admissible continuous overload
(Ib) and, of course, on the actual load (I)
tm
=
(1-60)min.
I
=
computed current
Ip
=
preheating current
Ib
=
continuously admissible current
(1-1.3)Im, step 0.01Im
Im
=
motor rated current
(0.1-1.5)In, step 0.1In
- Steady motor cooling-down time constant: to = (1-10)tm, step 1tm
The cooling-down time constant of the motor when running is “tm”; it is automatically changed
to " to " when the motor current drops below 0.1 lm (running/steady motor discrimination
level).
- Thermal prealarm : Ta/n = (50-110)%Tn, step 1%Tn
An alarm signal is issued when the simulated warming exceeds the set percentage of the
motor rated temperature Tn.
Automatic 1% drop out percentage.
- Restart inhibition: Ts/n = (40-100)%Tn, step 1%Tn
To inhibit a new motor starting before cooling down to 99% Ts/n, reset after tripping of the
thermal element takes places when T< 0.99[Ts].
22
3IsIdI 









22
22
(Ib/Im)(I/Im)
(Ip/Im)(I/Im)
In tm t