EDI 242E Betriebshandbuch - Seite 6

Blättern Sie online oder laden Sie pdf Betriebshandbuch für Industrielle Elektrik EDI 242E herunter. EDI 242E 13 Seiten. Enhanced dc isolator unit

Model 242E

Operations Manual

The MCU then controls the OUTPUT and DISPLAY blocks appropriately. If jumper SEL3 is

installed a valid input pulse will generate an output pulse of 100 milliseconds minimum.

The microcontroller also reads the state of the TEST switches on the front panel. If the

TEST switch is in the ON (locked) or MOM (momentary) position it will force the output to

the asserted (True) state regardless of the input circuit state. The TEST switches are

processed through the MCU for pulse width input and output requirements.

Valid output calls are made via optically isolated solid state transistors. Output calls are

indicated on the front panel by means of high intensity LEDs labeled "OUT".

The Model 242E operating voltage is generated by a high efficiency off-line switching

power supply. The VDD supply for the microcontroller and display elements results from a

post regulated 5 Vdc.

1.6.2 INPUT CIRCUIT

Resistors R5, R7, R11, and R12 [R6, R8, R13, and R17] provide the input bias and voltage

scaling circuit. The resulting voltage at U8.8 [U8.9] is then processed by the microcontroller

U8. Metal Oxide Varistor RV4 [RV5] provides input electrical transient protection.

The microcontroller U8 processes the input voltages to perform the voltage threshold and

pulse width filtering functions. All signal processing is performed in the digital domain and

controlled by firmware embedded in the microcontroller. This unit does not rely on analog

delay, pulse, or comparator circuits for processing the input signals.

The output driver Q2 [Q1] is isolated from both the AC Mains and the internal GND

reference of the Model 242E by opto-couplers U6 [U2]. CR1 [CR2] provides electrical

transient protection for the output driver Q2 [Q1].

The actual electrical state of the output circuit is monitored by the MCU via opto-coupler U7

[U3]. This output state is used to generate the FLT indicator status on DS1.4 [DS2.4].

The OUT LED indicator DS1.3 [DS2.3] for the channel output is driven directly from the

microcontroller U8. The input TEST switch SW4 [SW5] is read by the microcontroller U8

using strobe U8.19 [U8.18].

The main power supply is a fully isolated switching design. MOV RV7 provides electrical

transient protection. The AC Mains voltage is rectified and charges C3 to a nominal 170

Vdc. Controller U1 drives transformer T1 at approximately 144 KHz to produce an isolated

DC voltage at C15, C16, and C17. Inductor L1 and C14 filter the high frequency switching

Eberle Design Inc.

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