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Fire safety fans and the choice between 400V or 230/400V motors

Frequently asked questions by designers and assembly companies generally involve confusion related to the choice of a suitable three-phase motor for fire safety fans supplied by us. The choice of a motor depends on the operation of the fire safety fan that can be used for air-conditioning applications in a normal operation and for the outlet of smoke and combustion products in the event of fire.

1. Operation only during a fire. Power supply, power supply leads and the fan position are designed and implemented in such a way that the use of semiconductor backup sources is not necessary. Fans are supplied from independent transformer stations at the plant, by independent outlets from several directions, diesel aggregates, etc. Flow regulation by Y/D switching is not required. In such a case, standard motors can be used, denoted as 400 V (230/400 V alternative is also possible). Thermal insulations of winding must be disabled.

 2. Operation for current air-conditioning applications and fire safety ventilation For current air-conditioning operation, regulation by Y/D switching is required. Power supply, power supply leads and the fan position are designed and implemented in such a way that the use of semiconductor backup sources is not necessary. Fans are supplied from independent transformer stations at the plant, by independent outlets from several directions, Diesel aggregates , etc. In such a case, standard motors can be used, denoted as 400 VY/D pole-changing. In the event of fire, it is necessary to bypass the thermal protections in the winding in a safety manner.

3. Use for current air-conditioning and fire safety ventilation, power supply by the inverter. Electric power supply requires the use of semiconductor backup sources (inverters)

- If the inverter outlet is AC 3x400V, it is necessary to use standard motors supplied by us and denoted as 400V; in the event of fire, it is necessary to bypass thermal protections in the winding. It is necessary to indicate the use of inverter in the order; the manufacturer will supply a design suitable for converters.

- If the inverter outlet is AC 3x230V, it is necessary to use standard motors supplied by us to a special order only and denoted as 230/400V; in the event of fire, it is necessary to bypass thermal protections in the winding in a safe manner. It is necessary to indicate the use of inverter in the order; the manufacturer will supply a design suitable for converters.

General information about motors.
Fans supplied by us are equipped with three-phase motors, indicated in the information on the working voltage in one of the two following manners [the data pertain only to operation in energy networks with a delta voltage of 400V (380 to 415 V)].

Specification 230/400 V means that the motor can be operated only with winding in the star connection (delta connection leads to motor destruction).

Specification 400 V means that the motor can be operated only with winding in the delta connection (if the manufacturer denotes the Y/D delta connection in the manual, the fan can be operated permanently with low or high speed). If it is not recommended for regulation by the manufacturer, it can be operated only in the delta connection.
The 400 V pole-changing winding (Y/D) is expedient for a cheap regulation of the fan speed and thus also of its flow rate.

Attention.
If you do not require operating the fan with electronic frequency converters, it is necessary to specify this in the order. Motors are exposed to a considerable wear by converters; for this reason, they require a special design of insulation. When supplied from converters and inverters, magnetic circuits, winding and insulation are subject to strain by the high amplitudes of higher harmonic frequencies, which are the product of the pulse width modulation of the output voltage in converters.
 

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