mpec SA380-IT, Руководство пользователя

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N = N leg circuit connection.
FE = Functional earth circuit connection.
V = Internal voltmeter.
V = Measurement pulse voltage.
m
i = Resistance to earth ammeter.
m
R = Resistance to earth (B leg).
B
R = Resistance to earth (N leg).
N
C = System leakage capacitance (B leg).
B
C = System leakage capacitance (N leg).
N
An independent solid-state switch exists for each monitored circuit.
Independent internal protection resistors (94 k) exist for each monitored circuit.
Independent resistive cables (47 k) are provided for connection of each monitored circuit.
The modes of operation, and measurement principals of the SA380-IT are described in the following sections.
2.3) Modes of Operation
2.3.1 Normal Mode
Each monitored circuit (configured for measurement) is evaluated in turn, in a loop:
The monitored circuit is connected to the internal measurement circuitry and earth using a solid-state switch.
Voltage measurement is performed. (see 2.4)
If the voltage is in range, resistance to earth measurement is performed. (see 2.5)
The monitored circuit is disconnected from the internal measurement circuitry and earth.
the procedure is repeated for the next monitored circuit, and so on.
Every 60 seconds system integrity checks are performed:
Solid state switches are confirmed to be in the "open" state (all monitored circuits galvanically disconnected from each other,
measurement circuitry and earth).
The SA380-IT remains within its defined accuracy parameters (performs an internal calibration check).
Earth-loop resistance has not exceeded the alarm limit (resulting in inaccurate resistance to earth measurements).
2.3.2 Technicians Mode
For "on-site" use to aid a technician in locating and remedying monitored circuit faults. (see 4.4.3)
Forces the SA380-IT to make repeated measurements of a single monitored circuit.
Response time is increased as only the monitored circuit of interested is measured.
A large and clear read-out of measured values is reported to the technicians iPhone or computer display.
The technician can quickly verify if their actions are having the desired effect upon the monitored circuit.
Technicians mode can be cleared manually by the user at any time.
Technicians mode will automatically clear after a period of 4 hours, and the SA380-IT will resume "Normal mode".
Earth Loop resistance measurement and system safety tests are
performed whilst in technicians mode. not
2.3.3 Suspended Mode
The user may suspend monitored circuit measurement to enable fault finding activities to take place. (See section 4.4.5). This prevents the
SA380-IT injecting a measurement pulse, or presenting resistances to earth across the monitored circuits.
During suspended mode, all monitored circuits remain galvanically isolated from each other, all internal measurement circuitry and
earth.
Suspended mode can be cleared manually by the user at any time.
Suspended mode will automatically clear after a period of 4 hours, and the SA380-IT will resume "Normal mode".
Earth Loop resistance measurement and system safety tests are
performed whilst in suspended mode. not
2.3.4 Degraded Modes
There are instances when the SA380-IT may suspend some, or all measurements. Degraded modes are applicable in normal and
technicians mode and are often due to the activation of device safety interlocks. See section 5.2 for more information.
Scenario Voltage Measurement
of Monitored Circuits
Resistance to Earth
Measurement
of Monitored Circuits
Earth Loop &
Safety Tests
Device boot No No No
Time not set No No No