Temp Load Calc

[Alwayslearningelec]

I came across this sheet for SOME temps loads. Point is it seems like a good way to calculate loads. I guess Kva is the way to go then convert into amps.

What is duty cycle? Actual load?

 

[Julius Right]

The motor manufactured for a continuous -functioning- rating may run infinitely at this load
[kW or HP] This is Continuous Duty.
NEC Part II. Motor Circuit Conductors
430.22 Single Motor.
(E) Other Then Continuous Duty.
IEC 60034-1 defines also this duty types:
5.2 Classes of rating:
5.2.1 Rating for continuous running duty
5.2.2 Rating for short-time duty
5.2.3 Rating for periodic duty
5.2.4 Rating for non-periodic duty
5.2.5 Rating for duty with discrete constant loads and speeds
5.2.6 Rating for equivalent loading

 

[herding_cats]

Interesting. Does this factor staring motor loads kVA, kVAr, A?

 

[Julius Right]

In N.E.C [National Electric Code] NFPA 70 the duty is in hours.
In IEC 60034-1 the duty definition is this:
duty
the statement of the load(s) to which the machine is subjected, including, if applicable,
starting, electric braking, no-load and rest and de-energized periods, and including their
durations and sequence in time.
The purchaser declares the duty using a code -for instance:

Duty type S2 – Short-time duty S2 60 min

Duty type S3 – Intermittent periodic duty S3 25%

Duty type S8 – Continuous-operation periodic duty with related load/speed changes :

S8 JM = 0,5 kg × m2 Jext = 6 kg × m2 16 kW 740 min−1 30 %

40 kW 1 460 min−1 30 %

25 kW 980 min−1 40 %