Help with relay and rain sensor

[redtail]

Hi i have a rain sensor i wish to use in closing my roof on the obsy.

The motor for closing is an 8 amp but the sensor has a relay rated at 2 amps.

 I figure i need to use a relay to power up the motor.

Problem is i dont know witch type .

Can anyone help.

Manufacturers Notes... M152

If the sensor plate gets wet by way of rain water contact or snow, it switches on an internal relay. Sun blinds may be retracted with that, skylights may be closed or a simple rain alarm can be given. The internal relay contacts are voltage free and only serve as a switching mechanism. The automatically heated surface of the sensor prevents any freezing or wetting of the sensor surface. Two installed LEDs indicate the function. Waterproof-encapsulated electronics. .

Technical data...

 

Operating voltage 12 V/DC Current consumption without / with heating ca. 8 / 160 mA Relay contact 1 x ON, maximum load 25 V, 2 A Sensor heating automatically in case of contact with rain Light-emitting diode 1 indication that the rain sensor works Light-emitting diode 2 indication that rain is reported and the relay has switched on Duty cycle of the relay as long as the sensor is wet The module is encapsulated waterproof. Active sensor surface, gold-plated ca. 29 x 30 mm Dimensions ca. 65 x 45 x 36 mm

~~~~~~~~~~~~~~~~~~~~~~~~~~~~ th

[Gina]

If your roof motor runs off 12v a car relay will do the job - plenty available on ebay etc.

[astromerlin]

A relay like this should do.

http://www.ebay.co.uk/itm/12v-30A-40A-5-Pin-Automotive-Relay-Amp-Car-Van-Motorbike-Boat-/251099847620?pt=UK_In_Car_Technology&hash=item3a76b79bc4

[redtail]

Sorry forgot to say that the motor is 24 volts @ 8 amps

[cosmojaydee]

Commercial vehicles use 24v systems

[pete_l]

Sorry forgot to say that the motor is 24 volts @ 8 amps

Two points.

First, While you can get relays rated at 24V 8A, I'd play it safe and de-rate both the voltage and the current capability by a factor of 2. That will mean the relay isn't operating anywhere close to its limits which will prolong its life and improve its reliability. The price doesn't change much, either.

Second. Don't forget to put a diode (flyback suppression) across the coil of the relay.

Finally: some background.

There's a difference between ratings for A.C. power and D.C.

Also, some abbreviations:

SPST - single pole, single throw. The relay will switch 1 wire: either on or off

SPDT - single pole, double throw. The relay will switch 1 wire to one of two terminals, let's call them A and B - what you connect them to is up to you

DPDT - double pole, double throw. The relay will switch 2 wires, each to either an A or a B which are electrically independent. Handy for reversing the direction of a motor.

Here's a link to a suitable relay: http://www.rapidonline.com/electronic-components/finder-48v-relay-miniature-sdpt-dc-16a-60-1045

Rapidonline is a good supply of a wide range of parts.

[redtail]

Two points.

First, While you can get relays rated at 24V 8A, I'd play it safe and de-rate both the voltage and the current capability by a factor of 2. That will mean the relay isn't operating anywhere close to its limits which will prolong its life and improve its reliability. The price doesn't change much, either.

Second. Don't forget to put a diode (flyback suppression) across the coil of the relay.

Finally: some background.

There's a difference between ratings for A.C. power and D.C.

Also, some abbreviations:

SPST - single pole, single throw. The relay will switch 1 wire: either on or off

SPDT - single pole, double throw. The relay will switch 1 wire to one of two terminals, let's call them A and B - what you connect them to is up to you

DPDT - double pole, double throw. The relay will switch 2 wires, each to either an A or a B which are electrically independent. Handy for reversing the direction of a motor.

Here's a link to a suitable relay: http://www.rapidonline.com/electronic-components/finder-48v-relay-miniature-sdpt-dc-16a-60-1045

Rapidonline is a good supply of a wide range of parts.

Excellent-- thank you.