User's Manual

Applications

Motor monitoring with PTC in the

winding:

• For long starting and braking

operations

• For high switching frequencies

• For increased ambient tempera-

tures

• When the cooling medium flow

is restricted

• For AC drive operation

Highlights

• All products are PTB-ATEX

certified

• Wire breakage and short circuit

in the sensor circuit are displayed

• Versions with hard-gold-plated

relays which are electronics

compatible

• Favorably priced compact device

(A1 + 11 jumpered)

• Either screw or cage clamp termi-

nal connection system

The power and lifetime of motors is essentially limited by the winding temperature. Motor

manufacturers integrate PTC sensors in the motor winding if more stringent requirements prevail – e. g.

for high ambient temperatures or where cooling is restricted. The thermistor motor protection devices

operate according to the closed-circuit principle, detect these limit temperatures and switch the output

relay contacts.

Electrical Engineering from A to Z

SIMIREL relays

SIMIREL –

3RN1 thermistor motor protection

relay : Today, motor protection is so simple

PAGE 1
Applications Motor monitoring with PTC in the winding: • For long starting and braking operations • For high switching frequencies • For increased ambient temperatures • When the cooling medium flow is restricted • For AC drive operation Highlights SIMIREL – 3RN1 thermistor motor protection r e l ay : Today, motor protection is so simple The power and lifetime of motors is essentially limited by the winding temperature.
PAGE 2
S SIMIREL 3RN1 thermistor motor protection for PTC thermistor temperature sensors Screw connection Thermistor motor protection relays for PTC thermistors (type A PTCs) • Monostable version (closed-circuit principle), trips when the control voltage fails • All relays (with AC/DC 24 V) have electrical isolation RESET Contacts Auto 1 CO • 22.5 mm wide Power supply voltage Vs 50/60 Hz V AC Order No.