INCREASED SAFETY MOTORS Ex (e)
The motors of increased safety design (type ME) have been
developed from the standard TEFC, 3-Phase cage induction motors (type MA) for operation
in hazardous locations classified as zone-2 areas as per IS:5572 and VDE 0165
Limited Temperatures : Limited temperatures for insulation and all parts
as specified in IS : 6381 are given in Table 4.
| Temp.
Class |
T1 |
T2 |
T3 |
T4 |
T5 |
T6 |
| Lower limit of
Ignition Temp (0C) |
450 |
300 |
200 |
135 |
100 |
85 |
| Limited Temp. of
rotor at end of the time tE (0C) |
450 |
300 |
200 |
135 |
100 |
85 |
| Limited temp. of
stator : Class B |
185 |
185 |
185 |
135 |
100 |
85 |
Winding at the end
of time : Class F
end of time tE (0C) |
210 |
210 |
200 |
135 |
100 |
85 |
Limited temp. of
stator winding in
Continuous operation (0C) Class B
Class F |
110
130 |
110
130 |
110
130 |
110
110 |
100
100 |
85
85 |
Manufacturing Range :-
ME motors are designed for temperature class (Ignition Temperature Group) T3,
Motor types, frame sizes, outputs and other performance details are furnished in
the performance / selection tables.
Time 'tE' of Increased Safety Motors :-
Time 'tE' is the locked rotor withstand
time. It is the time taken for heating up any part of the motor from the
steady state temperature up to the limiting temperature under the locked rotor
condition. This time is determined separately for stator and rotor and the
minimum one is taken as the tE.
The current dependent protective devices must be so selected that the stalled
motor will be disconnected positively within the time tE, temperature class and
starting current are indicated on the name plate of ME motors.
The starting time normally permitted for these
motors is upto 1.5 times the time tE i.e. upto 1.5 x tE. If starting time
is approximately of the order of tE, motor protection becomes difficult, since
over current protection may operate spuriously in a repeated start. Hence,
for heavy and frequent starting, an enquiry should be made starting :
a) Duty Cycle
b) GD2 value of driven equipment referred to motor, and
c) Speed-Torque characteristic of the driven equipment.
Increased Safety motors have time tE of minimum 5 seconds.
| Voltage |
Single or
dual voltage from 110V to 660V |
| Frequency |
Ranging from 25Hz to 60 Hz |
| Attitude |
Higher than
1000M from mean sea level. |
| Output |
Dual output /Dual speed with
dahlander connection or separate winding. |
| Shaft |
Longer shaft
lesser diameter. |
| Construction |
B6, B7, B8, V1, V3, V5, V6,
B3/B5 |
| Anti
Condensation Heater |
For all
frame sizes. |
| Cable entry* |
Plug & socket arrangement
for all frame sizes. |
| Re-greasing
arrangement* |
For all
frame sizes above and including MJ 160 |
| Flameproof motor
for crane duty application can also be offered against enquiries. |
| *
Only for FLP motors |
|
