Test Plan Example of a Power System

The following is a section of a test plan recently developed for a power system. Names, designators, and values have been omitted or changed to protect the customer's IP. However, we hope the example provides an idea of the detail and depth we at Nine Dot Connects can provide. In this example, not only did we write the test plan, we will be executing upon it as well.

1) The AC Board consists of low-level component/cluster validation/verification functions by sheet

    a) Sheet 1 is essentially connectors in a hierarchical overview:

• Verify J1 connectivity with circuitry on other pages.
  

• Verify J7 (Main AC Power Connector) connectivity with circuitry on other pages. (This appears to be implemented as P4 (HOT) and P4 (NEUT) Banana Jacks on the PCB, which are not on the schematic.)
  

• Verify J10 (HV Connector) connectivity with circuitry on sub-sheets. (This appears to be implemented as P6 (DC_POS) and P9 (DC_NEG) Banana Jacks on the PCB, which are not on the schematic.)
  

• Verify that hierarchically-implied connectivity between sub-sheets is implemented on the PCB.
  

    b) Sheet 2 is all resistive AC dividers:

• Verify AC_HOT_SW divider is 594Kohms +/-0.1%.
  

• Verify AC_NEUT_SW divider is 594Kohms +/-0.1%.
  

• Verify AC_HOT divider is 594Kohms +/-0.1%.
  

• Verify AC_NEUT_DIV2 divider is 594Kohms +/-0.1%.
  

• Verify AC_NEUT_DIV3 divider is 594Kohms +/-0.1%.
  

• Verify AC_NEUT_DIV4 divider is 594Kohms +/-0.1%.
  

• Verify AC_NEUT_DIV1 divider is 6.00Megohms +/-0.1%.
  

• Verify GND_CHASSIS_DIV divider is 6.00Megohms +/-0.1%.
  

    c) Sheet 3 is AC Input protection, switching and current sensing.

• With the power disconnected, verify the resistance between AC_HOT and AC_NEUT is less than 994Kohms (R2+R8+R4).
  

• Verify that from AC_HOT to Pin 2 of the bridge rectifier is open.
  

• Verify that from AC_NEUT to Pin 3 of the bridge rectifier is open.
  

• Apply +15V to RELAY_HOT J4 pin 7 w.r.t. GND_HV (J4 pins 19 or 21) to activate relay K1.
  

• Verify that from AC_HOT to Pin 2 of the bridge rectifier (BR1) is now shorted (<0.1 Ohm).
  

• Switch +15V from RELAY_HOT (J4 pin 7) to RELAY NEUT (J4 pin 5) to deactivate relay K1 and activate relay K2.
  

• Verify that from AC_NEUT (P4) to Pin 3 of the bridge rectifier (BR1) is now shorted (<0.1 Ohm).
  

• Remove +15V.
  

• Turn down a Variac to zero and attach it in series with a 2K Ohm 20W power resistor across the AC input (P1 & P4) thru an AC current meter.
  

• Also attach an AC voltmeter across the AC input to monitor RMS input voltage.
  

• Attach a DC voltmeter across the rectified output + (P7) and (P8).
  

• Turn on the Variac and gradually bring up the Variac to no more than a few percent (say 5VRMS).
  

• Verify that the output voltage remains near zero.
  

• Turn down the Variac to zero again.
  

• Apply +15V to both RELAY_HOT and RELAY_NEUT (J1 pins 3 and 8) w.r.t GND_HV (J4 pins 18 and/or 22).
  

• Turn on the Variac and gradually bring it up again to no more than a few percent (say 5VRMS).
  

• Verify that the output DC voltage is now roughly 1.8 times the input ACRMS voltage minus 1.0-1.7V (~5.7V) and that no significant currents are flowing and nothing is getting hot. (The 4K power resistor should draw about 5.7mA.)
  

     Special Note: 1uF capacitors C10, C11, and C12 can collectively draw up to 192mA reactive current at 120VAC 60Hz.

• Gradually increase the Variac voltage monitoring currents and temperatures. Note that the 1K 20W resistor will become thermally overstressed somewhere in the 70V range, so it would be best to keep it below 60VACRMS.
  

    d) Sheet 4 is AC into a Pi-type common mode filter, followed by a bridge rectifier into a (moderately) small capacitor set (400nF).

• This was also tested in the steps of 'c)' above by applying low voltage AC (from a Variac) and verifying it is rectified to a DC voltage of the correct polarity within a1-2 volts of the AC peak at the output connectors.
  

• Verify that none of these components run hot in the latter tests of 'c)' above. This is best done with a spot temperature meter, if available.
  

• It would be informative to test common-mode rejection of the pi filter by injecting a sweep of high-frequency currents at the input to the bridge and verifying the resulting currents on the AC line input, but this really belongs to another set of tests needing to be done at the end during validation testing using certified laboratories and equipment. Hence it is not recommended here.
  

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