AUMA SA 6 - Motor Protection

Motor Protection
Output Speeds
Self Locking
Control Equipment
Motor winding may get overheated if the
actuator is run beyond rated duty or if the
rotor is stalled for considerably longer time or
if too high ambient temperature is
encountered. In order to protect the motor
against over heating, thermo switches are
embedded in the windings of three phase,
single phase AC motors and DC motors. When
integrated into the control circuits, they will
protect the motor against damage due to
The thermo switches interrupt the control
circuit as soon as winding temperature of
o
140 C is exceeded. After cooling down to a
o
temperature of approx. 110 C, the actuator can
be switched on once again. PTC thermistors
excessive winding temperature.
can also be provided for motor protection.
With large range of available output speeds,
almost every required operating time can be
The actuator output speed is determined by
the motor speed, change gears and reduction
The output speeds are available from 4 - 180
During trial run, if found necessary, the
output speed can be easily changed by
rpm in geometric progression of 1: 1.4.
gear ratio of worm / worm wheel.
achieved with Auma actuators.
Auma multi turn actuators SA/SAR3 to
SA/SAR100 are self locking (see note below)
with exception of output speeds 125 & 180
rpm. Actuators with 125 & 180 rpm are having
double start worm drive. After torque switch is
tripped, the sliding worm may move back to
initial position by the action of torque
measuring springs. This allows torque switch
to be released. If control system provides
continuous signal, this results in hunting of
motor. This can be avoided by the use of
auxiliary relay.
Note : The motor protection device must be
integrated into the controls, otherwise warranty
for motor is not valid.
Note on Self Locking :
Self-locking gearing does not ensure safe
stopping after an operation. If this is required,
separate locking arrangement must be provided.
Technical Data
AC Voltage
o
Tripping Temp 140 C
o
Reset Temp 90 - 110 C
Switch Rating
2.5 A
1.6 A
250 V AC
Cos O = 0.6
250 V AC
Cos O = 1
For higher velocities it is recommended to use
spring loaded stem nut type AF (special design).
exchanging the change wheels and or motor at
site. The grease filled housing need not be
opened for this purpose. The torque switch
setting & limit switch setting remains the same.
For actuators with output drive A (Stem nut),
max. permissible stem velocity must be
-
-
for gate valves max. 500 mm/min
for globe valves max. 250 mm/min
observed:
15