Danfoss MP 55E Data sheet

Data Sheet

Diﬀerential pressure switch Type MP 55E

MP 55E oil dierential pressure switches are used as safety switches

MP 55E oil dierential pressure switches are used as safety switches to protect refrigeration compressors against low lubricating oil pressure.

If the oil pressure fails the oil dierential pressure control stops the compressor.

MP 55E for HCFC, HFC and HC refrigerants are equipped with gold-plated SPDT contacts, which react directly on the dierential pressure without time delay.

The units are designed to operate in explosive zones acc. to 2014/34/EU, Atex directive, explosive zone 2, surface equipment, category

MP 55E are delivered with ¼ inch solder connections to ensure a hermetic installation.

Features

• Wide regulating range,

• Can be used for deep freeze, refrigeration and air conditioning plant,

• Can be used for HCFC, HFC and HC refrigerants,

• Electrical connection at the front of the unit,

• Screwed cable entry for cables from 6 – 14 mm diameter,

• Small contact dierential

AI217686432357en-001001

345

Connection to oil pressure side of lubrication

system, OIL

Connection to suction side of refrigeration plant,

Setting disc

Test device

Terminals

Features

Specication

Stainless steel

19/11, no. 1.4306 to EN 10088

Deep-drawn steel plate

no. 1.0338 to EN 10130

Free cutting steel

no. 1.0401 to EN 10277

Dierential pressure switch, Type MP 55E

Product specications

Design and Materials

Figure 1: Design for Type MP 55E

The MP 55E pressure control only switches the dierential pressure, i.e. the dierence in pressure between the two counteracting bellows, and it is virtually independent of the absolute pressure acting on both bellows.

The MP 55E can be set for dierent dierential pressures by the setting disc (3).

The set dierential pressure can be read from the internal scale.

Table 1: Materials in contact with the medium

Features

Specication

Ambient temperature

-20 – 60 °C

Max. working pressure

PS/MWP = 17 bar

Max. test pressure

Pe = 22 bar

Screwed cable entry

Pg 13.5

Cable diameter

6 – 14 mm

Max. media temperature

80 °C

Enclosure

IP20 to EN 60529 / IEC 60529

Contact rating

Pi max: 1 W

Ui max: 30 V

Ii max: 0.1 A

Ci max: 0.5 nF

Li max: 0.2 μH

EX - zone

Non EX - zone

Electrical data for intrinsically safe specication

(for all MP 55E types):

EX certified Zenner barrier

Pi max: 1 W Ui max: 30 V Ii max: 0.1 A

Ci max: 0.5 nF Li max: 0.2 µH

Dierential pressure switch, Type MP 55E

Technical data

Table 2: Technical data for MP 55E

Electrical connection

The MP 55E pressure switch placed in explosive zone must always be wired through reliable Ex zener barrier, placed outside ex-zone, to ensure insucient energy supply to cause the ignition of surrounding atmosphere by an electrical spark or the heating of components of circuitry.

The equipment to be used for electrical load limiting must always be approved for use in the zone concerned. Cables and cable entries approved for the application must be used and can not be in contact with sharp edges. Cables must be connected with adequate stress relief that way that pulling forces can not be carried throug the cable to the terminal.

 NOTE:

A particular system can be classied in dierent zones, for dierent parts of the system.

Intrinsic safety protection method

Table 3: Intrinsic safety protection method

Must be used with certied Ex ic barrier (product matching) satisfying the input parameters.

Installation and maintenance

Only authorised persons, who are certied in installing and maintaining the systems may do the installation, maintenance and change of the switch.

In the event of strong pulsation in the system, bellows must be protected against fatigue failure by use of damping coil.

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