Siemens EF6 Series Bedienungsanleitung PDF herunterladen (Seite 14)

3RN1 Thermistor Motor Protection

for overheating protection

Thermistor motor protection relays provide

decisive advantages where current-dependent

protection using either a circuit-breaker or an

overload relay is not the ideal solution: In

some cases, often as a result of external ef-

fects, overheating can occur without being

detected by the thermal image in the circuit-

breaker or an overload relay. Examples include

heavy-duty starting (e.g. centrifuges), opera-

tion with AC drive converters or frequent

switching, braking operations or when cooling

is restricted, e.g. due to accumulated dirt.

Your advantages:

• The motor winding temperature is directly measured

• Only one relay is required for all motor

power ratings

• Device/terminal labeling acc. to DIN EN 50005 for

“standard” switching relays and for overload

protective devices

• Relays with hard-gold-plated contacts for use under

difficult conditions

• LEDs indicate wire breakage and short circuit in the

sensor circuit

• All relay versions are equipped with screw terminals

or innovative spring-loaded terminals

• Version with protective separation up to 300 V

according to DIN/VDE 0106 as well as versions with

bistable relay for special applications

• ATEX certification for gases and dust

• All versions have removable terminals

Application areas:

• “Alarm and trip” function by using two sensor

circuits with different response temperatures – this

means that it is possible to respond before shutting-

down (additional cooling can be switched-in, the

load reduced, etc.)

• Multi-motor protection using only one device, e.g.

for conveyor lines – for several motors that must be

shutdown together

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Siemens EF6 Series Bedienungsanleitung Seite 14