Heath Consultants Heath Volume Corrector (HVC) - Manual (Page 9)

9
HVC 325 units are shipped from the factory, powered up and ready to install (Unless otherwise
specified).
The HVC 325 incorporates an on board uninterruptible power supply. This consists of one factory
installed “AA” lithium cell (BT1) rated at 3.6 volts. This cell is easily replaced in the field.
The HVC incorporates an on board battery (CR2032) for backup of the profiler log. This consists of a
replaceable button style lithium battery (BT2) located on the component side of the PCB.
Normal battery voltage should be displayed between the ranges of 1.5 to 1.7 volts for a new battery, and
when the primary power drops below .8 volts, the unit will switch to lithium backup. Under normal
conditions, the main battery pack should last up to four years and the lithium backup battery should last
up to 1 year without power from the main battery.
Caution: The maximum voltage allowed on the “Main battery” input is 2 volts DC. Only use the 1.5
volt battery pack supplied by Heath. If this voltage is exceeded, a protection fuse may blow and the
warranty will be void.
Note: If all three batteries lose power, the data that is stored in non- volatile memory will not be lost.
This includes Calibration, Poly (transducer) and configuration data.
Caution: To maintain the Intrinsic Safe rating, use only proper replacement batteries: main battery pack
HPN 77R91-1037, Lithium backup battery, HPN 77R65-8001, and coin battery, HPN 77R65-8002.
Contact Heath Consultants for replacement batteries and main battery packs. Refer to Annual Checks on
page 28 for replacement procedure.
External Power
The HVC can be connected to an external power source (6- 15VDC). External Power is
recommended when using modems which are externally powered.
Pulse Outputs
Form “A” (Standard)
The HVC 325 is equipped to provide pulse outputs representative of uncorrected and corrected volume.
There are two pulse channels available and are designated “A” and “B”. The pulse outputs are two-wire
open drain. Pulser A is designated for uncorrected pulse out. Pulser B is designated for corrected pulse
out.
Specifications for Pulsers
Pulse output electrical specification is as follows: Open drain, requires external 1 to 30 volts
maximum, 25 mA maximum, and 1 K minimum load resistance. Each pulse has a standard fixed pulse
width of 62.5 milliseconds with a duty cycle of 50% (62.5 ms on and 62.5 ms off). An optional 1000
milliseconds (1 sec) pulse width is also available.
Because of the wide variety of applications requiring connection to the pulse output channels,
consideration should be given to the site electrical classification as to the use of intrinsic safety barriers.