Connection Of The Thermal Protection Devices - WEG W22 Premium E3 Manual De Instalación, Operación Y Mantenimiento

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All protection devices, including overcurrent protection, must be set according to the rated machine conditions.
These protection devices must protect the machine against short circuit, phase fault or locked rotor condition.
The motor protection devices intended for use in hazardous areas must be set according to the applicable
standards.
Delta connected motors must be protected against phase fault. To do that, connect the overload relay in series
to the winding phases and set it to 0.58 times the rated current.
Check the direction of rotation of the motor shaft. If there is no limitation for the use of unidirectional fans, the
shaft rotation direction can be changed by reversing any two of the phase connections. For single-phase motor,
check the connection diagram indicated on the motor nameplate.

6.10. CONNECTION OF THE THERMAL PROTECTION DEVICES

If the motor is supplied with temperature monitoring devices, such as, thermostat, thermistors, automatic
thermal protectors, Pt-100 (RTD), etc., they must be connected to the corresponding control devices as
specified on the accessory nameplates. The non-compliance with this procedure may void the product
warranty and cause serious material damages.
All thermal protections (RTDs, bimetal thermal protectors and thermistors for stator protection) used in the
motor protection circuit must be connected as a simple equipment in and intrinsically safe circuit.
Motors driven by frequency inverters must have their winding thermal protections connected.
For other starting methods, the use of the thermal protections is optional.
Do not apply test voltage above 2.5 V on thermistors and current above 1 mA on RTDs (Pt-100)
according to IEC 60751 standard.
Figure 6.14 and Figure 6.15 show the connection diagram of the bimetal thermal protector (thermostats) and
thermistors, respectively.
In applications with protection by increased safety "Ex e", the protection device, in case of overload or locked
rotor, must trip with time delay based on the current along with monitoring the three external leads. The time-
"t " indicated on the motor nameplate should not be exceeded.
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If motors with protection by increased safety "Ex e" are submitted to acceleration time > 1.7x time-"t
must be protected by protection devices against overcurrent.
100 Manual of Electric Motors
Figure 6.14 - Connection of the bimetal thermal protectors (thermostats)
Figure 6.15 – Thermistor connection
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