19
O&M Manual
Rev-E (5/17)
Part 4 – Electrical Installation
4.1
General
The Q46 is powered in one of two ways, depending on the version purchased. The 12-24 VDC
powered analyzer requires a customer supplied DC power supply. The 90-260 VAC version
requires line power. Please verify the type of unit before connecting any power.
WARNING:
Do not connect AC line power to a 12-24 VDC powered unit. Severe
damage will result.
Important Notes:
1.
Use wiring practices that conform to all national, state and local electrical codes. For
proper safety as well as stable measuring performance, it is important that the earth
ground connection be made to a solid ground point from TB7. The AC power supply
contains a single 630mA slo-blo fuse (Wickmann/Littlefuse #372-0630). The fuse
F1
is located adjacent to
TB7
and is easily replaceable.
2.
Do NOT run sensor cables or instrument 4-20 mA output wiring in the same conduit
that contains AC power wiring. AC power wiring should be run in a dedicated conduit
to prevent electrical noise from coupling with the instrumentation signals.
3.
This analyzer must be installed by specifically trained personnel in accordance with
relevant local codes and instructions contained in this operating manual. Observe
the analyzer's technical specifications and input ratings. Proper electrical
disconnection means must be provided prior to the electrical power connected to this
instrument, such as a circuit breaker - rated 250 VAC, 2 A minimum. If one line of
the line power mains is not neutral, use a double-pole mains switch to disconnect the
analyzer.
4.
Repeated problems with lightning strikes damaging sensitive instrumentation are
often attributed to poorly bonded earth grounds in the instrument power source. The
protection schemes incorporated into this analyzer cannot operate to maximum
efficiency unless the ground connection is at its’ absolute lowest impedance.
There is no standard ground resistance universally recognized. Many agencies
recommend a ground resistance value of 5 ohms or less. The NEC recommends an
impedance to ground of less than 25 ohms, and less than 5 ohms where sensitive
equipment is installed. Power sources feeding sensitive instruments like the
Q46H/79PR should have the lowest possible impedance to ground.
