Weschler offers its VX-252, VC-252, and VR3-252 edgewise instruments for use in the nuclear industry. Boasting a rugged design and calibrating ability to 1% accuracy, the 252 class are magnetically shielded with self-contained inputs and a scale length of 4 ½ inches. These instruments adhere to IEEE standard 420-1973 and can be expected to meet or exceed seismic qualifications as stipulated by IEEE Standard 344. As analog meters they use the standard taut-band suspension system that has been recycled throughout the last several decades, as analog meters became the standard measurement devices in nuclear I&C rooms sometime in the mid 1950’s.
Well, that was nearly 70 years ago, and that standard, frankly, is no longer the standard. It is well-documented that since the turn of the 21st century and even before, digital instrumentation as largely replaced their analog ancestors in terms of improved reliability, accuracy, and functionality—but to nuclear I&C engineers and managers tasked with not only running the plant, but also maintaining profitability, overcoming analog obsolescence is only half of the problem facing the industry. Under NRC operational mandates, these old analogs, as well as their newer digital counterparts, require multiple spare units to support each and every meter being used in the control room, as well as the simulator. Quite simply, this adds up to millions of dollars sunk into spare inventory that rarely, if ever, generate and return on investment by being put into use. So how does one combat analog obsolescence, while at the same time maintaining a healthy maintenance budget and profitability?
Weschler VX252 
PNP-9
The answer is a digital instrument that does both. Otek’s Plug & Play meter is that very answer. The PNP-9 model is designed to replace both the VX252 as well as any meter ranging from 1½” to any size or shape of meter in the I&C room and simulator. It accomplishes this by using the universal input assembly, known as the HUB, that accepts any signal or power offered, by just selecting signal conditioners (up to four per I/O module) that cover over 50 input signals and either 100% signal power like analog meters (such as current loops [4-20 & 10-50 mA], VAC to 260V, VDC to 300V, AC Amps to 5Amps (AC & DC, Watts & Hertz). For units requiring external power (such as RTD, TD, S-G, pH, ORP, etc.) or even 4-20mA retransmission, PNP technology uses universal power modules that are plugged, inside the hub, into the instrument, requiring no solder or otherwise alteration to the surrounding wiring and panel displays that might void certification.
General specifications include a 4½ digit display, ± 0.5% accuracy of the full scale ±1 LSD, temperature coefficient: ± 50 PPM/°C, an operating temp of -20 to +70°C, CMRR: >90dB@ 50-60Hz, humidity levels of 5-95% (non-condensing), front panel options for NEMA 3 or NEMA 4X, EMI/RFI Class1E adherence, power requirements for loop powered options at >10<100mW and external requirements at >50<200mW, with a conversion rate of 3 seconds, and recalibration suggested every 2 years. Additionally, PNP meters make use of Otek’s newly designed “Sticky” scale plate designs, which allows the user to change the scale plate of any instrument to any color, language, or scale, simply by peeling off the old design and affixing the new scale plate onto the front cover of the instrument—all without having to open the instrument itself.
For more information on the PNP or other replacement instrumentation, please call (520) 748-7900 or email sales@otekcorp.com