How to choose the best hand dryers - Part 2

In the first part of this blog, we discussed various types of motors used in hand dryers, their features, performance and how they affect the cost of the hand dryers.

After the motor, the next factors which play a part in the quality of the hand dryer is the electronics used.

In a BLDC motor, the life of motor largely depends on electronics as electronics control the rotation speed. The polarity of the magnets are switched electronically to rotate motor at desired RPM. Hence BLDC motors are costly because it employs lots of electronics. A well designed BLDC motor has advantages over traditional motors.

Control Circuit of BLDC Motor

It should also be checked if the hand dryer control circuit uses solid state relay (SSR) or electro-mechanical relays. SSR use SCR or MOSFETS to switch the current instead of the electro-megnetic coils used in traditional relays. Tranditional relays, due to their mechanical limitation, have lesser life as compared to the SSRs which are being widely used today due to their longer life which increases the product life and less maintenance costs. But like all good things in life, SSRs come at the cost and they are usually 5-10 times more expensive than mechanical relays.

Solid State Relay
Solid State Relay

Electro-mechanical Relay

Also certain smart features that the hand dryers may have, like showing self diagnostic indications via LEDs or buzzer, auto-cut offs and over heating cut-off may employ additional electronics and sensors. These make the hand dryers smart and often prevent damage to the hand dryer incase of misuse or abuse.

Different types of sensors can be used in hand dryers to sense the user. Typically they are Infrared sensors or capacitive sensors. Capacitive sensors do not require direct line of sight to the user and can detect users across a metal or plastic surface. Both types of sensors are very accurate these days. However capacitive sensors are more rugged as less affected by any stray light which can be problem with IR if incorrectly used.

To summarize, below features provide value and improve product quality and service life and but at the same time also increase the cost of the product:

1) BLDC motor

2) SSR or Electromechanical relay

3) Features like auto-cut off, over heating protection for motor and heating coil, water tray full indication, carbon brush replacement or air filter replacement indication

4) IR Sensor or Capacitive sensors

Ankit Shah

Director, Sales and Product Development

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