Specifications Model 552 Catalog No. Model Power 55-0665 552 115 VAC, 50-60 Hz 55-0673 552A 230 VAC, 50-60 Hz Input - Single-ended, DC coupled 0 to +10V. Signal source can be Floating (not referenced to chassis GND), if necessary. INPUT CIRCUIT is protected from over-voltage ( 15V). Input Impedance - 100,000 Ω Gain - Unity Gain (1:1) Signal Transfer Accuracy - (Input to output): ± 1% F.S. End-Point Linearity - ±5% F.S., when used with HACO SCR-speed control Isolation Leakage - With 120 VAC, 60 Hz applied between input and output, less than 30 microamps. Output - 0 to +10V signal, not referenced to chassis (AC) ground Power - 100-130 VAC 50/60 Hz, 10 W Dimensions, H x W x D - 7.9 x 18.3 x 20.3 cm (3-1/8 x 7-3/16 x 8 in) Weight - (3 lb, 2 oz) 1
Features Model # 552 is designed to interface with all present Harvard Pumps that use an electronic motor speed control and DC motor manufactured later than 1975 and before 1990. Models manufactured later than 1990 can be modified by special request to accept the #552 modulator. Customers are advised to order 552 modulator and appropriate pump together. The Model 552 is connected to pump via a plug and jack. The factory will install a connector on the pump and calibrate speed control to match 552 so pump will run properly. See page 8 for instructions to retrofit existing pumps. Otherwise, a jack is sent with each 552 modulator when ordered alone. The modulator is an AC powered, magnetic amplifier that controls or modulates the existing pump speed control by either adding or subtracting voltage. Model 552 can be used in a variety of modes. 2
Applications Mode #1 - Remote Speed Control In this application the pump speed can be changed remotely by using the speed knob of the modulator in place of the normal speed knob on the pump. In this mode the pump speed control is always in the zero position. Mode #2 - Lower Limit Control In this mode the pump modulator speed knob can be used to set an absolute lower speed level that cannot be reduced or lowered by the pump speed control. Mode #3 - Voltage Control of Pump Motor Speed Using the input voltage feature of Model 552 a DC voltage from 0 to +10 volts can be used t o control the pump motor speed over its full range. A typical application might involve a process or sensor output instructing the pump to speed up or slow down. The modulator only responds to positive voltages. A negative voltage has no effect on speed. 3
Modulator Front Panel Controls and Features Power switch and pilot light - Controls and indicates AC power to the unit. (fig. 1 #3, #5) 2 1 5 3 INPUT +10V MAX. FOR MAX. SPEED SPEED CONTROL 50 ON SET PUMP RATE TO MIN. DESIRED SPEED 0 100 POWER 552 HARVARD APPARATUS PUMP SPEED MODULATOR 4 ure 1 Fig Speed control knob - Used to adjust pump motor speed. (fig. 1, #1) Input binding posts Red - positive Black - negative (fig. 1, #2) (NOTE - Max input for maximum speed is +10 volts DC). Cable - A nine foot, two conductor cable from the modulator to the pump. (fig. 1, #4) 4
Operating Instructions Connect both pump and modulator to an AC power source consistent with the voltage/frequency rating found on the serial number label. Mode #1 - Remote Control Set pump speed control to zero Set modulator speed to zero Turn on AC power to both modulator and pump Use modulator control only to vary pump speed NOTE - The actual motor speed is proportional to the sum of readings on both pump and modulator speed controls. If this sum exceeds 100 then the motor will be running in excess of its top speed rating causing motor burn out. CAUTION - The sum of both speed controls must never exceed 100. Mode #2 - Lower Limit Control Set modulator control to zero Set pump speed to the basal or low limit rate. The pump will never run below this rate Using the modulator control the pump speed can be increased above the basal rate NOTE - In this mode it is possible to exceed 100 and cause motor damage. Mode #3 - Voltage Control of Motor Speed Set pump speed to zero Set modulator speed to zero Apply a single ended DC signal voltage, floating, of between 0 and +10 volts to the input binding posts The pump motor will run at a speed proportional to the input signal. A positive 10 volts will produce a maximum motor speed (100%) while a zero voltage will stop the motor. A 5 volt signal will produce a motor speed of 50% CAUTION - Care must be taken to keep pump speed control at zero to avoid damage to motor. Negative signals have no effect on speed. 5
Supplemental Instructions To retrofit existing Harvard Pumps to fit Model 552 Pump Speed Modulator: 1. To use a Model 552 with existing variable speed pumps - A. Knock out silver button on control panel marked 552. B. Install female connector furnished with the Model 552. C. Attach chain to screw cap to closest screw head. D. Run wires from connector to motor control terminal board as follows: Connector Board Pin 1 ---------------------- Pin 7 Pin 2 ---------------------- Pin 8 2. Refer to Instruction Booklet for operation of Model 552. 6