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2 Introduction

2.1 Brief description

Thermostats control and monitor thermal processes. The devices of the EM series are available as tem-

perature controllers TR, temperature monitors TW, temperature limiters TB, safety temperature monitors

STW (STB), and safety temperature limiter STB. In the event of a malfunction, the STB switches the

monitored machine to a safe operating status.

Panel-mounted thermostats operate according to the fluid expansion principle – a microswitch is used

as an electrical switching element.

Switching functions

Temperature controller TR, temperature monitor TW, and safety temperatur monitor STW

If the temperature on the temperature probe exceeds the setpoint value, the electrical circuit is opened

or closed by a microswitch. If the temperature falls below the selected setpoint value (by the switching

differential), the microswitch is reset to its initial position.

Temperature limiter TB and safety temperature limiter STB

If the temperature at the temperature sensor exceeds the set limit value, the electrical circuit is opened

or closed by a microswitch.

After the temperature has fallen below the limit value by approx. 10 % of the scale range (approx. 15 %

with setpoint setting >350 °C), the microswitch can be unlocked manually.

For set points above 120 °C, the set point adjusted on the STB must be secured against adjustment (e.g.

with a lead seal).

Self-monitoring for safety temperature limiter STB and safety temperature monitor STW (STB)

If the measuring system is destroyed (i.e. if the expansion fluid escapes) the pressure in the membrane

of the STB and STW (STB) drops and permanently opens the electrical circuit. Unlocking is then no lon-

ger possible.

When the STW (STB) and STB sensors cools down to the negative temperature range, the circuit 1 to 2

opens, but must be unlocked manually by the restart knob when the temperature rises. The STW (STB)

restarts automatically.

Use of the safety temperature monitor STW as a safety temperature limiter STB

The circuitry used with the thermostat must comply with DIN EN 14597 and VDE 0631.

2.2 Intended use

Versions according to DIN EN 14597:

• Temperature controller TR

• Temperature monitor TW

• Temperature limiter TB

• Safety temperature monitor STW (STB)

• Safety temperature limiter STB

Type examination according to:

• DIN EN 14597

• Pressure Equipment Directive (only for types EM-20, EM-30, EM-40, EM-50)

•UL

JUMO EM Series User Manual

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