The MTLx526 enables two separate IS circuits in a hazardous area to be contact controlled by one or two, on/off, control signals in a safe area. Applications include the calibration of strain–gauge bridges; changing the polarity (and thereby the tone) of an IS sounder; the testing of IS fire alarms; and the transfer of safe-area signals into an annunciator with IS input terminals not segregated from each other. The output–relay contacts are certified as non–energy–storing apparatus, and can be connected to any IS circuit without further certification, provided that separate IS circuits are such that they would remain safe if connected together.

SPECIFICATION

See also common specification

Number of channels

Two, fully floating

Location of control circuit

Safe area

Input/output characteristics

Contact/Logic mode

(Inputs suitable for switch contacts, an open–collector transistor or logic drive)

Power supply failure protection

Relays de–energised if supply fails

Response time

25ms nominal

Contacts (suitable for connection to IS circuits)

1–pole changeover per channel

Contact rating

250V ac, limited to 40V dc for IS applications, 2A (reactive loads must be suppressed)

Contact life expectancy

2 x 107 operations at maximum IS load

Relay drive (see switch setting table)

Choice of "loop-powered" or "contact/logic" control, for both channels, by switch selection. A further switch option ("1in2out") enables either input, in contact/logic mode, to activate both outputs.

LED indicators

Green: power indication

Yellow: two: output status, on when relay energised

Power requirement, Vs

41mA at 20V dc 44mA at 24V dc 60mA at 35V dc

Power dissipation within unit

1.1W maximum at 24V

Safety description (each channel)

Non-energy–storing apparatus: relay contacts may be connected to any IS circuit without further consideration

User switch settings for operating mode

MTL4526

MTL552