Ac On/Off Circuit Breaker On Mx Series Front Panel; Table 3-1: Suggested Input Wiring Sizes For Each Mx Cabinet - California Instruments MX30-1 User Manual

User Manual – Rev AJ
The input power cables and protective circuit breaker used must be large enough to handle the
input current and input voltage of the power source and must conform to local electrical codes.
C nsult a q o ualified electrician prior to installation. Table 3-1 shows the size of the cables that
may be used per MX cabinet. Note that wires must be sized to accommodate the worst-case
maximum current that may occur under low line c
require different wire types and sizes. These ratings should also be used when selecting a
circuit breaker or equivalent disconnect device.
Cable le ngths must not exceed twenty-five (25) feet. For lengths greater than 25 feet, calculate
the voltage drop from the following formula:
2 X DISTANCE X CABLE RESISTANCE PER FT. X CURRENT = VOLT DROP
Nominal Line
Voltage
480 V
400 V
230 V
208 V
* Using high temperature rated wire. Always consult the National Electrical Code and/or local code
regulations for proper rating and size of wire cabling prior to installation.
CAUTION: Capacitors in the power source may hold a hazardous electrical charge
even if the power source has been disconnected from the mains supply. Allow
capacitors to discharge to a safe voltage before touching exposed pins of mains
supply connectors.
Power modules need at least 15 Minutes to discharge to safe levels before they can
be removed.

3.5 AC On/Off Circuit Breaker on MX Series front panel.

It is important to understand the purpose and operation of the On/Off circuit breaker of the MX
Series located on the lower left side of the front panel. This is a 2A rated breaker that is used to
engage and protect the LV Power supply of the MX chassis only. The LV Power supply
provides DC bias power to the entire MX system. The AC input power is routed through a set of
three AC line fuses (F1, F2 and F3) located in the lower left bottom corner of the MX. (See
Figure 3-2 for fuse locations). These fuses protect the three MX amplifiers and the AC input
transformer from excessive input currents. The AC input power is connected to the input
transformer through a large three-pole contactor. Removing AC power to the LV Power Supply
by opening the front panel circuit breaker (moving the lever to the down (OFF) position) will
cause this contactor to loose its coil voltage and will result in it opening and disconnecting the
input transformer and amplifier from AC mains input.
Note: If any MX system failure has occurred on any part of the MX system, AC input
power must be removed immediately and
inspected by a qualifier service technician.
Always turn off the On/Off Circuit breaker before re-applying AC input power.
40

Table 3-1: Suggested Input Wiring Sizes for each MX Cabinet *

Load Current Wire Gauge (US)
@ low line
75 A
RMS
90 A
RMS
157 A
RMS
175 A
RMS
onditions. Local electrical codes may also
Circular Mils
(Kcmils)
6 AWG 26.24
4 AWG 41.74
2 AWG 66.36
1 AWG 83.69
not restored until the system has been
California Instruments
Metric (mm2)
13.3
21.1
33.6
42.4
MX Series