Simpatico: As an introduction to motor specifications, below is a typical HV motor nameplate.

Simplicio: Ex II 3 G CE:

Ex – symbol for equipment designed for potentially explosive atmosphere

II – explosion group (I – equipment group for mining application, II – equipment group for surface applications)

II 3 G – equipment group and category and type of explosive atmosphere (G – gas, D – dust)

Zone 0 – only category 1 equipment can be used, Zone 1 – category 1 or 2, zone 2 – category 1, 2 or 3

CE mark – European certification mark

Ex nA II T3, VTT 06 ATEX 084X:

Ex nA – Non-sparking, for use in Zone 2 only.

T3 – Equipment temperature class (The surface temperature of the equipment will not exceed 200⁰ C)

(The surface temperature or any parts of the electrical equipment that may be exposed to the hazardous atmosphere should be tested that it does not exceed 80% of the auto-ignition temperature of the specific gas or vapour in the area where the equipment is intended to be used)

VTT 06 ATEX 084X – Reference number for type test certificate (type being cage induction motors). The sign X signifies that the equipment is subject to certain conditions for safe use. VTT is the inspection body that does the test.

Type Test Certificate is issued when a component has passed all the relevant tests and meets all technical requirements.

IEC 450 L 120: Code to identify motor frame size

450 = Motor frame size (Distance of centre of shaft from the base)

L = Relative length of the frame (S, M or L). From the diagram, L denotes the relative size of the dimension 2F, which I think corresponds to the shaft length. (Please correct me if I am wrong)

From the table below, for 90S and 90L, if we take the ratio 2F/90, we get S= 1.11 and L=1.38

However, if we do the same for 112S, we don’t get the same ratio for S. I would like to know what S, M and L actually represent.

120 = Tried hard but could not find

 

S1: IEC duty cycle code for continuous operation, at constant load, so that the equipment reaches thermal equilibrium

Temperature rise class B: Temperature rise characteristic of the motor, when it is operated under rated conditions. Class B means maximum temperature rise of 80⁰ C over the ambient temperature (taken as 40⁰ C). Maximum hot-spot temperature = 130⁰ C (10⁰ allowance)

Insulation class F: Thermal tolerance of the motor winding. Class F means temperature rise of 100⁰ C over the ambient temperature of 40⁰ C. Maximum hot-spot temperature = 155⁰ C (15⁰ C allowance)

RPM (1493): Rated RPM when motor is running at full load

6326/C3: Bearing code for drive end (end that drives the load)

6326 – One of the bearing code from the 6300 series

C3 – Internal clearance of bearings. Ranges from C1-C5, with C5 being the largest and C1 being the tightest. If not stated, clearance is taken as C2 or C3, which is for normal clearance.

6322/C3: Non-drive end

IC, IM, IE codes:

IC (International cooling): code to identify cooling method

IE (International efficiency): code to identify efficiency of equipment, IE1<IE2<IE3

IM (International mounting): code to identify mounting arrangement

Efficiency calculation:

Rated voltage = 6kV, Rated current = 80A, Power factor = 0.88

Rated output power = 710kW

Input power at rated conditions, Pin = 6*80*0.88*1.73 = 731.61

Efficiency = Pout/Pin = 0.97 or 97%

Finally, I was wondering – we have temperature rise class B and insulation class F, which means that the winding temperature won’t rise above 155⁰ C (limiting). And, we have equipment temperature class T3 (200⁰ C).

Is the T3 rating determined by the previous two parameters? Had we specified, for example, temperature rise class E and insulation class B (i.e. maximum 130⁰ C), would our equipment temperature class change to T4 (135⁰ C).

Simpatico: Excellent and comprehensive answer.

I have only some minor comments to add.

Ex nA II T3, VTT 06 ATEX 084X: (what does the II relate to? It is not the explosion group in this instance)

However, if we do the same for 112S, we don’t get the same ratio for S. I would like to know what S, M and L actually represent.

I think Short, Medium and Long. These seem to be Manufacturer’s designations for the frame length.

Finally, I was wondering – we have temperature rise class B and insulation class F, which means that the winding temperature won’t rise above 155⁰ C (limiting). And, we have equipment temperature class T3 (200⁰ C).

Is the T3 rating determined by the previous two parameters? (in part) Had we specified, for example, temperature rise class E and insulation class B (i.e. maximum 130⁰ C), would our equipment temperature class change to T4 (135⁰ C).

The Insulation Classes are used for many items of electrical equipment, not just those in hazardous areas, and are based on the ability of the insulation to withstand ageing and breakdown.

The Temperature Classes for the explosive atmospheres have totally different temperature breakpoints to suit the most commonly found ignitable materials.

There is clearly an informal relationship between the two.

You could not use a Class B insulation motor running at an average of 120deg.C in a T5 or T6 gas atmosphere.

Most motors are Class F anyway, but to get extended life and lower copper losses, most motors are specified to run no hotter that Class B.  These can be used in T3 (and probably T4) without restriction.

If you need a motor for T5 or T6 atmosphere, you would take a Class F motor and severely derated it so that it does not run hotter than the ignition temperature of the gas.

Simplicio: II here is the gas group. Gases are grouped under different categories depending on their properties.

Gas groups: I, IIA, IIB, IIC

IIC has gases are most volatile and require the least energy to get ignited. IIA require the most. Hence equipment designed for IIC can be used for IIC, IIB and IIA. If nothing is marked after II, like in this case, it can be used for any gas group.

Teacher: That right, II means it is suitable for use with any IIA, IIB or IIC gas/vapour.

The reason for this is that the motor is non-sparking.

You only need specify the gas groups IIA, IIB IIC for Exd or Exi types of equipment.

Useful Links (opens in a new window):
Motor Nameplate - NEMA vs IEC Standards
Wikipedia - Insulation System
Designation System International Cooling (IC) & Motor Cooling
Wikipedia - Premium Efficiency
International Mounting Arrangements
Bearing Handbook for Electric Motors & Bearing Radial Clearance Explained