Motor protection relay (over-current relay) 4.00/7.00 A - Riegler 103064

Motor protection relay (over-current relay) 4.00/7.00 A

Standards and origin

• Customs tariff number: 90329000
• Country of origin: PL

About Compressor pressure switches

A compressor pressure switch cuts the drive motor once the set upper pressure is reached in the receiver and restarts it when the pressure drops to the lower switching point. That makes it the central control element of a piston compressor and, in most versions, it also unloads the compressor head when switching off. The group is rated for medium temperatures from -5 °C to 80 °C.

What matters when choosing

• Version: AC design or three-phase design. The motor type of the compressor decides, as the two versions are not interchangeable. There are also versions without unloading valve for plants that already have a separate one.
• Setting range: documented ranges include 4 to 11 bar, 6 to 16 bar, 4 to 12 bar as well as 2 to 11 bar and 2.5 to 16 bar. The intended cut-out pressure should sit inside the range, not at its edge.
• Thread: G 1/4 IT or G 1/2 IT, matching the port on the receiver or on the check valve. Smaller switches with flange F4 1/4 go on G 1/4, the larger ones with F4 1/2 on G 1/2.
• Protection: IP 44 or IP 54, depending on where the unit stands. IP 54 is the higher grade for dusty or damp surroundings.
• Current rating and motor power: three-phase versions are graded by permissible motor current, for example 4 to 6.3 A, 6.3 to 10 A and 10 to 16 A, with further versions for 7.5 kW. The figure has to match the motor rating plate.

Typical applications

• Pressure control on piston compressors in workshops, trades and vehicle service
• Replacing a failed switch on an existing compressor
• Control of three-phase compressors in production plants
• Receiver installations where the compressor head is unloaded through a separate valve
• Mobile compressor units on trailers and service vehicles

The group holds 31 items for medium temperatures from -5 °C to 80 °C in protection classes IP 44 and IP 54. Production is in Poland and Germany.