Relays Series 59 Derivative Relays Introduction Features & Benefits Force-balance principle produces a proportional output for pneumatic circuit flexibility Derivative action compensates for process and measurement lags for stable pneumatic control Description The Series 59 Derivative Relays are pneumatic relays that operate on the force-balance principle. As such, they produce an output equal to the input signal plus or minus an amount proportional to the rate of input change. The direct derivative output is the input signal plus an amount proportional to the rate of the input change. Inverse derivative output is the input minus an amount proportional to the rate of the input change. Since the magnitude of the derivative response is proportional to the rate of input change, a steady rate of input change will make the output lead (or lag) the input by a definite time. This lead (or lag) time is the derivative time. The Model 59 is a 3 mode controller which includes an integral derivative section, where the derivative action on the input precedes proportional and reset responses. This arrangement, which is the only one that can prevent overshooting on startup, also provides the most effective control following any large load change. Minimum Output Pressure 0.3 psig with 20 psig supply Input/Output Ratio Specifications 1:1 (±0.5%) for steady state conditions Operating Range Response Level 3-15 psig normal (50 psig maximum for input and output) 0.01% of full scale Supply Pressure Less than 0.08 scfm at balance Normal: 20 psig Minimum: 3 psig above maximum output Maximum: 60 psig Pneumatic Maximum Overload Protection Ambient Temperature Limits 100 psig to any connection - 40 to 180°F (- 40 to 82°C) Air Consumption 7 Connections: 1/4" NPT 7.17 Relays Series 59 Derivative Relays Technical data Mounting Dimensions Model Designation Model Number Derivative Action Derivative Gain 59D Direct 59DF Direct, Fast 59DH1,2 Direct High Gain 59R Inverse 59RF Inverse, Fast Time (MINUTES) 6:1 .05-20 6:1 .005-2.0 30:1 .05-20 1:6 .05-20 1:6 .005-2.0 Derivative Needle Valve Graduations 0.5-20 .01-5 .05-20 .05-20 .01-5 7 1) Model 59DH cannot be converted to an inverse unit. 2) The derivative time of the Model 59DH may be further increased by adding an external volume chamber that connects into the side of the derivative unit. This volume chamber increases the needle valve setting by a factor of ten. 7.18